Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement

Determination and validation of design space for mesenchymal stem cell cultivation processes using prediction intervals

In regenerative medicine, mesenchymal stem cells (MSCs) constitute a promising therapeutic route for many diseases. The current quality-by-design guidelines do not clearly define a framework for MSC production. Here, we suggest and experimentally validate a model-based method to determine design spaces (DSs) for MSC cultivation. A kinetic model used in previous work was employed; part of the experimental data was used to re-estimate the maximum specific growth rate in the kinetic model and then calculate the prediction intervals of this parameter. Subsequently, regions of seeding density and harvesting time where both the upper and lower limits of growth predictions met the acceptable number of cells and confluency with given risk levels were defined as DSs. Finally, the established DS was validated with the remaining data; it allowed better predictions of the cell numbers and confluency under specific cultivation conditions and improved the overall robustness of MSC cultivation processes.

MSCs in Acute Kidney Injury Treatment: Modulating Mitochondrial Function and Inhibiting Pyroptosis via PGC-1α

OBJECTIVE

This study aims to investigate the mechanisms of MSC therapy for acute kidney injury, focusing on the regulation of mitochondrial function and pyroptosis in renal tubular epithelial cells (RTECs).

METHODS

An in vivo ischemia/reperfusion (I/R) model was used to assess the effects of MSC treatment on mitochondrial membrane potential, mitochondrial function, cell pyroptosis, and PGC-1α expression in RTECs.

RESULTS

MSCs significantly improved mitochondrial function in RTECs by upregulating PGC-1α expression, regulating mitochondrial fusion and fission proteins, reducing mitochondrial ROS production, and suppressing NLRP3 inflammasome activation. Furthermore, MSC treatment reduced the levels of pyroptotic markers, such as IL-18, and exhibited a marked anti-fibrotic effect in the long-term. These findings suggest that MSCs not only repair acute kidney injury but also offer long-term protection against fibrosis.

CONCLUSION

MSCs improve the repair of acute kidney injury by modulating mitochondrial function and inhibiting pyroptosis, providing new theoretical support for MSC-based therapies in AKI treatment.

Induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) inhibit M1 macrophage polarization and reduce alveolar bone loss associated with periodontitis

BACKGROUND

Periodontitis is a chronic inflammatory disease and macrophages play a pivotal role in the progression of periodontitis. Mesenchymal stem cells (MSCs) have emerged as potential therapeutic agents for the treatment of periodontitis due to their immunomodulatory properties and capacity for tissue regeneration. Compared to conventionally derived MSCs, induced pluripotent stem cell-derived MSCs (iMSCs) offer distinct advantages as promising candidates for MSC-based therapies, owing to their non-invasive acquisition methods and virtually unlimited availability. This study aims to investigate the effects and mechanisms of iMSCs in modulating macrophage polarization and alleviating periodontitis-related alveolar bone loss.

METHODS

iMSCs were generated from iPSCs and characterized for differentiation potential. The effects of iMSCs on macrophage polarization were evaluated using THP-1-derived macrophages under inflammatory conditions (LPS and IFN-γ stimulation). Co-culture assays, cytokine analysis, reactive oxygen species (ROS) detection, transcriptomic analysis, flow cytometry, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blot analysis were performed to elucidate the underlying mechanisms. The therapeutic potential of iMSCs was assessed in a ligature-induced periodontitis mouse model using micro-CT, histological analysis, and immunofluorescence staining.

RESULTS

iMSCs inhibit M1 macrophage polarization through the suppression of the NF-κB signaling pathway. Additionally, iMSCs reduce the production of pro-inflammatory cytokines (IL-1β, IL-17) and reactive oxygen species (ROS), while enhancing the secretion of anti-inflammatory cytokines (IL-10) and growth factors (VEGF), thereby improving the inflammatory microenvironment. Under inflammatory conditions, iMSCs preserve the osteogenic potential of periodontal ligament stem cells (PDLSCs) and alleviate alveolar bone loss in mice with periodontitis. In vivo, iMSCs reduce the number of M1 macrophages and inhibit the activation of NF-κB in periodontal tissues, supporting their anti-inflammatory and immunomodulatory effects.

CONCLUSION

iMSCs demonstrate significant therapeutic potential in periodontitis by modulating macrophage polarization, reducing oxidative stress, and mitigating alveolar bone loss associated with the disease. These findings provide new insights into the mechanisms of iMSCs and their application as cell-based therapies for periodontal diseases.

Inhibition of CD45-specific phosphatase activity restores the differentiation potential of aged mesenchymal stromal cells: implications in regenerative medicine

BACKGROUND

Aging affects the reparative potency of mesenchymal stem/stromal cells (MSCs) by diminishing their proliferation and differentiation capability; making them unsuitable for regenerative purposes. Earlier we showed that MSCs acquire the expression of CD45 as a consequence of aging, and this increased expression is associated with downregulated expression of osteogenic markers and upregulated expression of adipogenic and osteoclastogenic markers. However, whether CD45 is actively involved in the aging-mediated deregulated differentiation in the MSCs was not elucidated.

RESULTS

In the present study, we showed that pharmacological inhibition of CD45-specific phosphatase activity in the aged MSCs restores their differentiation potential to young-like. Investigation of the molecular mechanism involved in the process showed that several regulatory kinases like p38, p44/42, Src, and GSK3β are in their dephosphorylated form in the aged MSCs, and importantly, this status gets reversed by the application of a CD45-specific PTP inhibitor. Conversely, pharmacological inhibition of these kinases in young MSCs imposes an aged-like gene expression profile on them. Additionally, we also showed that the secretome of aged MSCs affects the viability and differentiation of primary chondrocytes, and this detrimental effect is reversed by treating aged MSCs with the PTP inhibitor. Our data demonstrate that the aging-mediated expression of CD45 in MSCs alters their differentiation profile by dephosphorylating several kinases and treating the aged MSCs with a CD45 PTP activity inhibitor rejuvenates them.

CONCLUSIONS

CD45 can be used as an aging marker for mesenchymal stem cells. Alteration of CD45 phosphatase activity could have significant implications for the use of MSCs in regenerative medicine.

Insights into the role of histone lysine demethylases in bone homeostasis and skeletal diseases: A review

Histone lysine demethylases (KDMs), as important epigenetic regulators, are involved in various biological processes such as energy metabolism, apoptosis, and autophagy. Recent research shows that KDMs activate or silence downstream target genes by removing lysine residues from histone tails, and participate in the regulation of bone marrow mesenchymal stem cells (BM-MSCs), osteoblasts (OB), osteoclasts (OC), chondrocytes and other skeletal cell development, differentiation and formation. Moreover, several members of the KDM family affect the occurrence and development of bone diseases such as osteoporosis (OP), osteoarthritis (OA), osteosarcoma (OS), by regulating target genes. Specific regulation mechanisms of KDMs suggest new strategies for bone disease treatment and prevention. Despite the unique function and importance of KDMs in the skeletal system, previous studies have never systematically summarized their specific role, molecular mechanism, and clinical treatment in bone physiology and pathology. Therefore, this review summarises the expression pattern, intracellular signal transduction, and mechanism of action of the KDM family in several bone physiological and pathological conditions, aiming to highlight the important role of KDMs in bone diseases and provide a reference for the future treatment of bone diseases.

Secretome from prolonged high-density human Wharton's jelly stem cell culture accelerates wound healing in both in vitro and in vivo models

The complex of biofactors secreted by mesenchymal stem cells, termed the secretome, can promote wound healing. Studies using this secretome often utilise material collected from short term and sub-confluent lab-scale cultures. Secretome was derived from prolonged culture of high-density industrial scale human Wharton's jelly stem cells and its effects on wound healing was assessed. In vitro cell proliferation and scratch closure assays showed that secretome treatment dose-dependently increased cell proliferation and promoted scratch closure. Subsequently, using biopsy punch, circular wounds were created on three-dimensional de-epidermised dermis human skin equivalent (in vitro) where secretome-treated wounds showed accelerated wound closure, and enhanced epithelial proliferation and differentiation were observed and quantified. In an in vivo rat acute wound model, secretome applied to the back of test animals greatly enhanced wound healing by promoting re-epithelialisation, vascularisation and granulation maturation. In conclusion, secretome derived from prolonged culture of high-density industrial scale two-dimensional human Wharton's jelly stem cells possesses potent wound healing properties. This could greatly lower the cost of production and facilitate development of highly efficacious secretome-based wound healing products.

Stromal Cells in Early Inflammation-Related Pancreatic Carcinogenesis-Biology and Its Potential Role in Therapeutic Targeting

The stroma of healthy pancreases contains various non-hematopoietic, non-endothelial mesenchymal cells. It is altered by chronic inflammation which in turn is a major contributor to the development of pancreatic adenocarcinoma (PDAC). In PDAC, the stroma plays a decisive and well-investigated role for tumor progression and therapy response. This review addresses the central role of stromal cells in the early inflammation-driven development of PDAC. It focuses on major subpopulations of pancreatic mesenchymal cells, i.e., fibroblasts, pancreatic stellate cells, and multipotent stroma cells, particularly their activation and functional alterations upon chronic inflammation including the development of different types of carcinoma-associated fibroblasts. In the second part, the current knowledge on the impact of activated stroma cells on acinar-to-ductal metaplasia and the transition to pancreatic intraepithelial neoplasia is summarized. Finally, putative strategies to target stroma cells and their signaling in early pancreatic carcinogenesis are reflected. In summary, the current data show that the activation of pancreatic stroma cells and the resulting fibrotic changes has pro- and anti-carcinogenetic effects but, overall, creates a carcinogenesis-promoting microenvironment. However, this is a dynamic process and the therapeutic targeting of specific pathways and cells requires in-depth knowledge of the molecular interplay of various cell types.

Rat Tracheal Cartilage Regeneration Using Mesenchymal Stem Cells Derived From Human iPS Cells

Tracheal cartilage provides structural support to the airways to enable breathing. However, it can become damaged or impaired, sometimes requiring surgical resection and reconstruction. Previously, we clinically applied an artificial trachea composed of a polypropylene mesh and collagen sponge, with a favorable postoperative course. However, the artificial trachea presents a limitation, as the mesh is not biodegradable and cannot be used in pediatric patients. Compared to a polypropylene mesh, regenerated cartilage represents an ideal material for reconstruction of the damaged trachea. The use of mesenchymal stem cells (MSCs) as a source for cartilage regeneration has gained widespread acceptance, but challenges such as the invasiveness of harvesting and limited cell supply persist. Therefore, we focused on the potential of human-induced pluripotent stem cell (hiPSC)-derived mesenchymal stem cells (iMSCs) for tracheal cartilage regeneration. In this study, we aimed to regenerate tracheal cartilage on an artificial trachea as a preliminary step to replace the polypropylene mesh. iMSCs were induced from hiPSCs through neural crest cells and transplanted with a polypropylene mesh covered with a collagen sponge into the damaged tracheal cartilage in immunodeficient rats. Human nuclear antigen (HNA)-positive cells were observed in all six rats at 4 weeks and in six out of seven rats at 12 weeks after transplantation, indicating that transplanted iMSCs survived within the tracheal cartilage defects of rats. The HNA-positive cells coexpressed SOX9, and type II collagen was detected around HNA-positive cells in four of six rats at 4 weeks and in three of seven rats at 12 weeks after transplantation, reflecting cartilage-like tissue regeneration. These results indicate that the transplanted iMSCs could differentiate into chondrogenic cells and promote tracheal cartilage regeneration. iMSC transplantation thus represents a promising approach for human tracheal reconstruction.

Role of the Wnt signaling pathway in the complex microenvironment of breast cancer and prospects for therapeutic potential (Review)

The focus on breast cancer treatment has shifted from the cytotoxic effects of single drugs on tumor cells to multidimensional multi‑pathway synergistic intervention strategies targeting the tumor microenvironment (TME). The activation of the Wnt signaling pathway in the TME of breast cancer cells serves a key regulatory role in tissue homeostasis and is a key driver of the carcinogenic process. Modulating the crosstalk between the Wnt pathway and TME of breast cancer is key for understanding the biological behavior of breast cancer and advancing the development of novel antitumor drugs. The present review aimed to summarize the complex mechanisms of the Wnt signaling pathway in the breast cancer TME, interactions between the Wnt signaling pathway and components of the breast cancer TME and breast cancer‑associated genes, as well as the interactions between the Wnt signaling pathway and other signaling cascades at the molecular level. Furthermore, the present review aimed to highlight the unique advantages of the Wnt signaling pathway in the macro‑regulation of the TME and the current therapeutic strategies targeting the Wnt signaling pathway, their potential clinical value and future research directions in breast cancer treatment.

Evaluation of the Safety and Regenerative Potential of Human Mesenchymal Stem Cells and Their Extracellular Vesicles in a Transgenic Pig Model of Cartilage-Bone Injury In Vivo - Preclinical Study

Osteoarthritis (OA) is a degenerative joint condition leading to disability. The lack of effective treatment for OA creates a need for the development of new therapeutic approaches that may rely on stem cells including mesenchymal stem/stromal cells (MSCs) and their derivatives such as extracellular vesicles (EVs). The objective of this study was to evaluate the impact of MSCs derived from adipose tissue (AT-MSCs) and umbilical cord (UC-MSCs) and their EVs on cartilage-bone injury in vivo, to identify the specimen with the highest regenerative potential for further clinical applications in patients with OA. Humanized pigs underwent cartilage-bone injuries followed by intraarticular administration of products containing AT-MSCs, UC-MSCs, AT-MSC-EVs or UC-MSC-EVs mixed with hyaluronic acid (HA) or HA alone (for comparison). After 6-m follow-up, almost-fully-healed cartilage-bone defects were observed in the AT-MSC- and UC-MSC-treated pigs, and the defects were filled primarily with hyaline cartilage. In AT-MSC-EV- and UC-MSC-EV-treated pigs, a partial cartilage-bone tissue repair was observed, and the defects were filled primarily with fibrocartilage. The control pigs demonstrated limited regeneration capacity. The microcomputed tomography parameters of the subchondral bone indicated the ongoing progression of OA in controls, whereas in the MSC- and MSC-EV-treated pigs, the parameters indicated the cessation of OA progression. Moreover, no serious side effects were observed after the administration of products containing MSCs or MSC-EVs. The results indicate the safety and regenerative activity of MSCs on injured tissues, which favors not only the healing and improvement of bone structure but also the formation of hyaline cartilage. Superior tissue repair was observed after the administration of products containing AT-MSCs. The treatment of OA with MSC-EVs needs further standardization.

Potential applications of mesenchymal stem cells in ocular surface immune-mediated disorders

We explore the interaction between corneal immunity and mesenchymal stem/stromal cells (MSCs) and their potential in treating corneal and ocular surface disorders. We outline the cornea's immune privilege mechanisms and the immunomodulatory substances involved. In this realm, MSCs are characterized by their immunomodulatory properties and regenerative potential, making them promising for therapeutic application. Therefore, we focus on the role of MSCs in immune-mediated corneal diseases such as dry eye disease, corneal transplantation rejection, limbal stem cell deficiency, and ocular graft-versus-host disease. Preclinical and clinical studies demonstrate MSCs' efficacy in promoting corneal healing and reducing inflammation in these conditions. Overall, we emphasize the potential of MSCs as innovative therapies in ophthalmology, offering promising solutions for managing various ocular surface pathologies.

The role of injections of mesenchymal stem cells as an augmentation tool in rotator cuff repair: a systematic review

Background

Arthroscopic repair is currently the gold standard for the surgical treatment of rotator cuff tears, but the retear rates remain unacceptably high. Mesenchymal stem cells (MSCs) may play a role in the local biology and enhance tendon-to-bone healing during rotator cuff repair. However, the scientific literature is still not well systematized on the effects of injection of MSCs as an augmentation tool for rotator cuff repair. Our goal was to investigate the effect of injections of MSCs to augment rotator cuff repair in patients with rotator cuff tear.

Methods

PubMed and EMBASE were searched up to June 2022 for clinical studies that applied MSCs injections to augment rotator cuff repair. Imaging, patient-reported outcomes measures, shoulder range of motion and strength were collected. Quantitative synthesis included within- and between-group mean differences with the within-group percentage of minimal clinically important difference for each study and continuous outcomes, and relative risks (RR) for retears and adverse events. Quantitative synthesis was computed with 95% confidence intervals (CIs).

Results

We included 5 studies comprising a total of 228 individuals with a weighted mean age of 59.3 ± 1.2 years. Three studies used bone marrow MSCs and two studies applied adipose-derived MSCs. Patient-reported outcomes measures, shoulder range of motion, and strength improved significantly in all MSCs groups, with minimal clinically important differences ranging from 120% to 679% of established cut-off. When compared to rotator cuff repair alone, the MSCs groups did not result in improved outcomes. The MSCs group showed significant protective effect at the mid-term (RR = 0.52, 95% CI 0.27-0.98) and long-term (RR = 0.24, 95% CI 0.11-0.53).

Conclusion

There are no differences in clinical and functional outcomes between rotator cuff repair with or without augmentation with MSCs. However, there may be a protective effect against retear at the mid-term and long-term follow-up when augmenting the repair with MSCs. The literature on this topic is still preliminary and the quality and certainty of evidence is limited.

Shear stress preconditioning enhances periodontal ligament stem cell survival

OBJECTIVE

The study investigated in vitro the influences of shear stress preconditioning on human periodontal ligament stem cells (hPDLSCs) under serum deprivation.

DESIGN

hPDLSCs were subjected to shear stress at 0.5 and 5 dyn/cm², both with and without serum starvation. Cell viability and apoptosis were assessed using the Resazurin assay and flow cytometry analysis, respectively. Gene and protein expressions were analysed by real-time polymerase chain reaction, immunofluorescent staining, and Western blotting.

RESULTS

Our results revealed that shear stress potentially mitigated serum derivation-induced cell death by inducing cell viability, enhancing colony formation, and inhibiting cell apoptosis. The addition of an ERK inhibitor inhibited the shear stress-induced cell apoptosis resistance. Shear stress treatment upregulated cell viability-related gene expression, including SOX2, SOD1 and BIRC5. In particular, shear stress promoted the nuclear translocation of SOX2. Meanwhile, the expression of BIRC5 was not inhibited by cycloheximide. Shear stress-induced SOX2 and BIRC5 expression was attenuated by PI3K and ERK inhibitors, respectively.

CONCLUSIONS

Shear stress contributes to promoting SOX2 and BIRC5 expression by hPDLSCs, implicating the promotion of stemness and cell survival under serum starvation.

Human cornea-derived mesenchymal stromal cells inhibit T cells through indoleamine 2,3 dioxygenase

Defining the mechanism of immune modulation by mesenchymal stromal cells (MSCs) from distinct anatomical tissues is of great translational interest. The human cornea is an immunologically privileged organ, and the mechanism of immunoregulation of cornea-derived MSCs (cMSCs) is currently unknown. We investigated cMSCs derived from the corneas of 5 independent human donorS for their fitness and mechanism of action in suppressing T cells. cMSCs display the immunophenotype CD45-CD73+CD105+CD90+CD44+ and robust in vitro growth. 30-plex secretome analysis identified that cMSCs innately secrete specific molecules in a dose-dependent manner. cMSCs do not express or upregulate costimulatory but do upregulate coinhibitory molecules upon stimulation with interferon γ (IFNγ). cMSCs inhibit T-cell proliferation in contact-dependent co-cultures, which can be predicted by a unique secretome signature. In addition, co-culturing in a 2-chamber transwell system has demonstrated that cMSCs also inhibit T-cell proliferation in a non-contact-dependent manner. Mechanistic analysis has demonstrated that activated T cells effectively induce indoleamine 2,3-dioxygenase (IDO) but not other enzymes of the tryptophan metabolic pathway in cMSCs. Silencing of IDO in cMSCs reduces their fitness to suppress T cells. These results provide evidence that in cMSCs, one of the principal mechanisms of immunosuppression on T cells is through IDO. These results suggest that MSCs derived from the human cornea display immunoregulatory properties and, thus, may play a role in maintaining the immune-privileged niche of the cornea.

The Supportive Role of Lymph Node Mesenchymal Stromal Cells in Follicular Lymphoma Involves the PITX1-hTERT-Podoplanin Axis

The microenvironment within lymph nodes plays a pivotal role in the pathogenesis of follicular lymphoma (FL), a malignancy characterized by the accumulation of neoplastic B cells. Here, we report that human FL lymph node mesenchymal stromal cells (FLSCs) display surface protein expression profiles consistent with the standard phenotypic criteria for human mesenchymal stromal/stem cells (MSCs), yet exhibit reduced mesenchymal differentiation capability. FLSCs did not show the typical immunomodulatory protein expression patterns observed in fibroblastic reticular cells, marginal reticular cells, or follicular dendritic cells, as they expressed chemokine (C-X-C motif) ligand 13 and podoplanin but lacked chemokine (C-C motif) ligand 19 and complement receptor 1/2. Functionally, FLSCs exhibited superior FL cell survival-supportive capability in cocultures compared with bone marrow MSCs. This supportive effect was reduced when the cell culture inserts were used. In addition, this supportive capability was accompanied by reduced levels of B-cell-supportive soluble factors such as interleukin-6, regardless of the presence of cell culture inserts. Thus, both cell-cell contact-dependent and -independent mechanisms are involved in this process. Comprehensive transcriptomic analysis revealed that transcription factor paired-like homeodomain 1 (PITX1) is downregulated in FLSCs. Given that PITX1 regulates human telomerase reverse transcriptase (hTERT) transcription, FLSCs exhibited longer telomeres and a higher population-doubling capacity than MSCs. Furthermore, FLSCs expressed elevated podoplanin, whereas MSCs did not. Notably, hTERT-transfected MSCs also showed increased podoplanin expression, suggesting a positive association between hTERT and podoplanin. In summary, our findings indicate that FLSCs deviate from classical MSCs in their differentiation potential and instead exhibit a protumorigenic phenotype. This phenotype supports FL cell survival and is potentially mediated by an aberrant PITX1-hTERT-podoplanin signaling axis. These results highlight the critical role of FLSCs in the FL lymph node microenvironment, with implications for understanding tumor-supportive niches in FL pathogenesis.

GelMA/HA-NB hydrogel encapsulating adipose-derived chondrogenic exosomes enhances enthesis regeneration in chronic rotator cuff tears

Chronic rotator cuff tears (RCTs) often lead to poor surgical outcomes, requiring innovative therapies. This study explores the potential of exosomes from chondrogenic stem/progenitor cells (CSPCs), encapsulated in a GelMA/HA-NB hydrogel, to improve rotator cuff healing. Adipose-derived stem cells (ASCs) were isolated and sorted to obtain CSPCs, from which exosomes (sub-Exos) were extracted and characterized. Unsorted ASCs exosomes (un-Exos) were also isolated for comparison. The hydrogel-exosome system was evaluated for biocompatibility, chondrogenic differentiation, and sustained release in vitro and in a chronic RCT rat model. 112 rats were divided into four groups: control, hydrogel alone, un-Exos with hydrogel, and sub-Exos with hydrogel. Healing was assessed at 4 and 8 weeks using micro-CT, histology, and biomechanical testing. In vitro, sub-Exos with hydrogel demonstrated excellent biocompatibility and enhanced chondrogenic potential. In vivo, sub-Exos were retained at the injury site for up to 14 days, significantly improving histological scores, bone mineral density, bone volume/total volume, and trabecular thickness. Biomechanical tests revealed superior failure load and stiffness in the sub-Exos group. These findings demonstrate that localized delivery of GelMA/HA-NB hydrogel-encapsulated sub-Exos significantly enhances enthesis healing, offering a promising cell-free therapeutic strategy for chronic RCTs.

Lack of IFN-γ response of human uterine myometrium-derived MSCs significantly improve multiple IBD parameters compared to bone marrow MSCs: Implications for anti-TNFα-refractory patients

The clinical efficacy of mesenchymal stem cell (MSC) therapy for inflammatory bowel disease (IBD) is inconsistent and often fails to match promising preclinical findings. To improve outcome, we compared MSCs isolated from human uterine myometrium (Ut), a readily-available tissue source from a unique immune niche, to bone marrow (BM) MSCs, the most common source, in a murine IBD model with mechanisms underlying differential effects. In this study, human BMMSCs and UtMSCs were intravenously administered to mice with dextran sulfate sodium-induced colitis and evaluated for disease activity, microbiome composition, and cellular immunity. Bioinformatics analyses including patient data were performed to further specify involved mechanisms with subsequent functional validation performed. We found that UtMSC but not BMMSC treatment significantly reversed disease parameters by improving microbiome and reducing mesenteric lymph node IFN-γ and IL-17A-secreting T cells. Transcriptomic analysis revealed UtMSCs had reduced MHC II pathway activation compared to BMMSCs. Functional validation confirmed UtMSCs compared to BMMSCs expressed lower IFN-γ receptors, prevent MHC II-mediated human unstimulated T cell activation, and modulated stimulated T helper (Th) cells away from effector phenotypes while increasing regulatory T cells (Tregs) and IL-10 levels. Bioinformatics from IBD patients resistant to non-T cell-specific therapies implicated persistent MHC II-mediated Th1/Th17 activation as key drivers of disease. Overall, UtMSCs outperformed BMMSCs in improving microbiota, avoiding IFN-γ responses, and modulating overall Th responses, suggesting this MSC source may offer more significant effectiveness for IBD and Th1/Th17-mediated conditions. Our findings also highlight that understanding MSC source-specific therapeutic mechanisms is crucial for optimizing clinical therapies.

Evaluation of Novel Therapeutic Agents for Modulation of the Inflammatory Response in Rotator Cuff Tendinopathy Utilizing a Mouse Model of Subacromial Impingement

BACKGROUND

Rotator cuff disease is prevalent and can cause significant disability. Local subacromial corticosteroid injections (CSIs) have been a mainstay of nonoperative management despite concerns regarding their potential for adverse effects on tendon and muscle tissue. We identified 3 potential molecular targets that could be inhibited by alternative, currently available treatments.

PURPOSE

To compare the effects of losartan (LOS), anakinra (AK), and alpha-2-macroglobulin (A2M), not previously utilized in the treatment of rotator cuff disease, with CSI-treated and nontreated controls in a murine model of rotator cuff tendinopathy.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 90 twelve-week-old male C57BL/6J mice were placed into 6 different groups (n = 15 mice per group). Group 1 underwent a sham procedure with no treatment (sham controls). Group 2 underwent placement of a metal clip in bilateral shoulders to induce impingement on the rotator cuff but received no further treatment. All mice receiving treatments (groups 3-6) underwent bilateral clip impingement surgery on day 0. On day 21, subacromial injections of CSI, AK, or A2M were performed, and LOS was administered via drinking water. All mice were sacrificed at 6 weeks after the initial impingement surgery. The supraspinatus tendons and muscles were harvested. Histology, biomechanical testing, flow cytometry, gene expression, and gait analysis were performed. The significance level was set at P = .05 for all statistical analyses.

RESULTS

Flow cytometry demonstrated that treatment groups exhibited individual stromal cell marker profiles more similar to sham controls than to the impingement control groups, with significantly higher percentages of CD51+, CD73+, CD90.2+, CD105+, and CD146+ cells compared with the impingement control group. Gene expression analysis demonstrated significantly decreased pathway scores for cytokine signaling, inflammasome, phagocytic cell function, oxidative stress, and proteotoxic stress in the treatment groups compared with the impingement control group.

CONCLUSION

These novel therapeutic agents may have utility in promoting a favorable environment for stromal progenitor cells and decreasing cytokine signaling, inflammatory responses, and stress pathways associated with subacromial impingement.

CLINICAL RELEVANCE

Further investigation into these agents and the underlying cellular and molecular mechanisms of inflammation may allow for the utilization of alternatives to CSIs.

Human stromal cell-based protocol to generate astrocytes: a straightforward in vitro predictive strategy in neurotoxicology

The inherent adaptability of human mesenchymal stromal cells (hMSCs) to differentiate into neural lineages provides a valuable resource for investigating potential neurotoxicity in humans. By harnessing the ability of hMSCs to transform into astrocytes, we can evaluate the effects of various agents on these vital cells. Our protocol employs hMSCs sourced from umbilical cord tissue, ensuring a readily available supply of high-quality cells. The hMSC-to-neural workflow encompasses six essential steps: hMSC culture, followed by the generation of embryoid bodies (EBs) from these cells on specialized surfaces. Next, EBs and cells are expanded in a growth-promoting medium, directing them toward neural lineages. Subsequent differentiation into immature astrocytes is achieved through the use of specific factors. The process continues with the maturation of EBs/cells into astrocyte-like cells (hALCs) under optimized conditions, culminating in the final development of hALCs in a specialized medium. This methodology yields cells that display astrocyte morphology and express characteristic markers such as GFAP and S100β. The protocol is efficient, requiring roughly 6 weeks to generate hALCs from primary hMSCs without genetic manipulation. The application of hMSCs in evaluating cell damage triggered by neurotoxicants like MeHg and MGO underscores their potential as a valuable component within a more extensive battery of neurotoxicity tests.

Mesenchymal Stem Cell-Derived Exosomes: A Promising Therapeutic Strategy for Age-Related Diseases

The global increase in the aging population has led to a concurrent rise in the incidence of age-related diseases, posing substantial challenges to healthcare systems and affecting the well-being of the elderly. Identifying and securing effective treatments has become an urgent priority. In this context, mesenchymal stem cell-derived exosomes (MSC-Exos) have emerged as a promising and innovative modality in the field of anti-aging medicine, offering a multifaceted therapeutic approach. MSC-Exos demonstrate significant potential due to their immunomodulatory and anti-inflammatory properties, their ability to inhibit oxidative stress, and their reparative effects on senescent tissues. These attributes make them valuable in combating a range of conditions associated with aging, such as cardiovascular diseases, neurodegeneration, skin aging, and osteoarthritis. The integration of exosomes with membrane-penetrating peptides introduces a novel strategy for the delivery of biomolecules, surmounting traditional cellular barriers and enhancing therapeutic efficacy. This review provides a comprehensive synthesis of the current understanding of MSC-Exos, underscoring their role as a novel and potent therapeutic strategy against the intricate challenges of age-related diseases.

Human Umbilical Cord Mesenchymal Stem Cells for the Treatment of Systemic Lupus Erythematosus via Glucose Metabolism of CD4+T Cells

BACKGROUND

T cells play a crucial role in the pathogenesis of systemic lupus erythematosus (SLE), with their functions regulated by various metabolic pathways. This study explores SLE pathogenesis and the therapeutic effects of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) via metabolic reprogramming.

METHODS

Clinical data and peripheral blood samples were collected from 15 SLE patients and matched healthy controls. CD4+ T cells were isolated and activated in vitro with anti-CD3/CD28. Following 72 h of co-culture with hUC-MSCs, CD4+ T cell viability was assessed using the CCK-8 assay. The oxygen consumption rate (OCR) and glycolytic proton efflux rate (glycoPER) were measured with a Seahorse analyzer. Cytokine levels were detected by multiplex assay, and transcriptome sequencing was performed. Western blotting analyzed glucose metabolism-related enzymes and signaling pathways in lupus model mice.

RESULTS

Compared to healthy controls, activated CD4+ T cells from SLE patients exhibited significantly increased OCR and glycoPER levels (P < 0.05). Following 72 h of co-culture with hUC-MSCs, OCR, glycoPER, cell viability, and pro-inflammatory factors in SLE-CD4+ T cells decreased markedly (P < 0.01). Upregulation of 434 genes and downregulation of 172 genes was observed, particularly in the JAK-STAT and PI3K-Akt pathways. hUC-MSCs inhibited the expression of glucose metabolism-related enzymes and the JAK-STAT and PI3K-Akt signaling pathways in lupus model mice.

CONCLUSION

hUC-MSCs inhibited the proliferation and function of aberrant CD4+ T cells in SLE patients by modulating glycometabolism and the JAK-STAT and PI3K-Akt signaling pathways, providing new insights into the therapeutic mechanisms of MSCs based on metabolic reprogramming.

DSUP modified mesenchymal stem cells exert significant radiation protective effect by enhancing the hematopoietic niche

BACKGROUND

Radiation induced hematopoietic failure was the primary cause of death after exposure to a moderate or high dose of whole body irradiation, causing increased challenge for nuclear or radiological treatment, so it is an urgent need to develop radioprotectors for attenuating hematopoietic damage caused by acute radiation syndrome (ARS). Given the excellent therapeutic effects and special benefits of mesenchymal stem cells (MSCs) in radiation damaged hematopoietic stem/progenitor cells (HSPCs) recovery and hematopoietic niche reconstruction, enhancing the hematopoietic niche with the radiotolerance MSCs can be an alternative solution to prevent and attenuate hematopoietic radiation damage, which needs to be studied.

METHODS

Here, we constructed MSCs modified with Damage Suppressor Protein (DSUP), a radiotolerance gene identified from tardigrade Ramazzotius varieornatus, and verify its radiation protection effect in HSPCs-MSCs co-culture model in vitro and radiation damaged mice model in vivo.

RESULTS

Our results showed that DSUP protein had no significant toxic side effects on the basic stemness properties and differentiation potential of MSCs, and significantly enhanced the radiation tolerance and DNA protection ability of MSCs. Compared with the control (CON) group MSCs, the DSUP modified MSCs after radiation damage suffered less DNA damage, preserved most of proliferation activity and migration ability. In the HSPCs-MSCs co-culture model, DSUP modified MSCs have significant protective effect on HSPCs by providing a functional hematopoietic niche after radiation damage. The DSUP group irradiated HSPCs exhibited more rapid recovery, the higher HSPCs ratio and better hematopoietic differentiation potential. In animal studies, pre infusion of DSUP modified MSCs reduce irradiated mice mortality rate, reduce hematopoietic failure incidence, and provide a protective effect against radiation injury by protecting hematopoietic microenvironment and promoting HSCs recovery. DSUP modified MSCs can be used as a radioprotector and existed significant radiation protection effect for ARS at doses below 7 Gy total-body irradiation (TBI) of X-ray in both immunodeficient and immunocompetent mice models.

CONCLUSIONS

DSUP modified MSCs may serve as a new radioprotector for ARS. DSUP modified MSCs could attenuate radiation damage of HSPCs and promote HSPCs rapid recovery as well as hematopoietic reconstruction by providing a more functional niche after radiation, thereby reducing the occurrence of hematopoietic failure and improving survival rate.

Biodentine Stimulates Calcium-Dependent Osteogenic Differentiation of Mesenchymal Stromal Cells from Periapical Lesions

Biodentine, a tricalcium silicate cement, has emerged as a retrograde root-end filling material to promote periapical lesion (PL) healing after apicoectomy. However, its underlying mechanisms remain unclear. This study tested the hypothesis that Biodentine stimulates the osteogenic differentiation of mesenchymal stromal cells (MSCs) derived from PLs. The Biodentine extract (B-Ex) was prepared by incubating polymerized Biodentine in RPMI medium (0.2 g/mL) for three days at 37 °C. B-Ex, containing both released microparticles and soluble components, was incubated with PL-MSCs cultured in either a basal MSC medium or suboptimal osteogenic medium. Osteogenic differentiation was assessed by Alizarin Red staining and the expression of 20 osteoblastogenesis-related genes. Non-cytotoxic concentrations of B-Ex stimulated the proliferation of PL-MSCs and induced their osteogenic differentiation in a dose-dependent manner, with a significantly enhanced effect in suboptimal osteogenic medium. B-Ex upregulated most early and late osteoblastic genes. However, the differentiation process was prolonged, as indicated by the delayed expression of wingless-type MMTV integration site family member 2 (WNT2), bone gamma-carboxyglutamate protein (BGLAP), bone morphogenic protein-2 (BMP-2), growth hormone receptor (GHR), and FOS-like 2, AP-1 transcription factor subunit (FOSL2), compared with their expression under optimal osteogenic conditions. The stimulatory effect of B-Ex was primarily calcium dependent, as it was reduced by 85% when B-Ex was treated with the calcium-chelating agent EGTA. In conclusion, Biodentine promotes the osteogenic differentiation of PL-MSCs in a calcium-dependent manner, supporting its stimulatory role in periapical healing.

Protecting and rejuvenating ageing skin by regulating endogenous hyaluronan metabolism using adipose-derived stem cell-secreted siRNAs

Background

Loss of moisture is the primary cause of skin ageing and dysfunction. The skin's hydration largely depends on hyaluronan (HA) and its ability to retain water. Ultraviolet (UV) irradiation, which accounts for 80% of skin ageing (commonly referred to as photoaging), gradually disrupts the balance of HA metabolism, leading to a reduction in HA levels, dehydration, and, ultimately, the formation of wrinkles.

Methods

In this study, we develop an RNAi-based strategy to treat aged skin by modulating endogenous HA metabolism. Hyaluronidase 2 (HYAL2), an enzyme responsible for HA degradation, is selected as the therapeutic target, given its significant upregulation in photoaged skin. To deliver the siRNA targeting HYAL2 to the skin, human adipose-derived stem cells (ADSCs) are engineered to stably express and secrete HYAL2-targeting siRNAs (ADSC/siRH) via small extracellular vesicles (sEVs).

Results

In vitro experiments demonstrate that ADSC-delivered siRNAs are successfully internalised by recipient cells, where they restore UV-induced HA reduction by inhibiting HYAL2 expression. In vivo experiments revealed that subcutaneous implantation of engineered ADSCs prior to UV exposure significantly protects mouse skin from accelerated HA degradation, helping to retain water content and prevent UV-induced dryness. Furthermore, the application of engineered ADSCs to aged mouse skin can markedly restore HA and water content, effectively smoothing deep wrinkles and improving skin appearance.

Conclusion

We developed an effective biological strategy to combat skin ageing and damage by preserving endogenous HA levels, which could be applied for facial rejuvenation in the future.

Investigating the regulation of the miR-199a-3p/TGF-β/Smad signaling pathway by BSHXF drug-containing serum combined with ADSCs for delaying intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) significantly contributes to low back pain (LBP), yet effective treatment options are scarce. BSHXF, a classical traditional Chinese medicine formula, demonstrates dual pharmacological actions: tonifying kidneys, strengthening bones, activating blood circulation, and resolving stasis. It has been widely used in IDD management. Given its potential, combining BSHXF with miRNA regulation and stem cell therapy may enhance therapeutic outcomes by targeting molecular and cellular pathways underlying IDD pathogenesis.

Aim of the study

IDD is recognized as one of the primary causes of low back pain, yet effective therapeutic interventions for this condition remain limited. This study explores the role of BSHXF drug-containing serum combined with adipose-derived stem cells (ADSCs) in slowing IDD progression via the miR-199a-3p/TGF-β/Smad signaling pathway. By comprehensively investigating the synergistic effects of this combination therapy, we aim to propose a novel multi-target strategy that addresses the complex pathogenesis of IDD.

Materials and Methods

This study employed a combination of in vivo and in vitro models. An IDD model was induced in rat caudal intervertebral discs through needle puncture, while an oxidative stress-induced ADSCs injury model was created in vitro using tert-butyl hydroperoxide (T-BHP). Cell viability was measured with the CCK-8 assay. Cell cycle distribution and mitochondrial reactive oxygen species (ROS) levels were assessed using flow cytometry. Cellular senescence was assessed using SA-β-galactosidase staining. Lactate dehydrogenase (LDH) activity was quantified to evaluate cellular damage. Differentiation into nucleus pulposus-like cells was assessed using immunofluorescence double staining for CD73 and COL2A1. ELISA was used to measure inflammatory cytokines (TNF-α, IL-1β, IL-4, IL-10) in cell supernatants. miR-199a-3p expression was determined using RT-qPCR. Western blotting was employed to quantify COL2A1, SOX9, and ACAN protein levels, reflecting nucleus pulposus-like differentiation and extracellular matrix (ECM) synthesis capacity. Western blotting was employed to assess pathway activity by analyzing the protein expressions of TGF-β1, Smad2, Smad3, and their phosphorylated forms, P-Smad2 and P-Smad3. In vivo experiments assessed histopathological degeneration through hematoxylin-eosin (HE) and Safranin O-Fast Green staining. Immunohistochemistry (IHC) analyzed COL1A1 and COL2A1 expression levels. RT-qPCR quantified miR-199a-3p expression. Western blotting was employed to assess the expression levels of TGF-β1, Smad2, Smad3, P-Smad2, and P-Smad3 for pathway regulation evaluation.

Results

Our experimental results demonstrated that serum containing BSHXF significantly alleviated T-BHP-induced oxidative stress, improved the cellular microenvironment, promoted ADSCs proliferation, and decelerated cellular senescence. Further mechanistic analysis revealed that BSHXF significantly activated the TGF-β/Smad signaling pathway, driving the differentiation of ADSCs into nucleus pulposus-like cells and restoring normal cell cycle progression. Overexpression of miR-199a-3p inhibited the TGF-β/Smad pathway, leading to ECM degradation and elevated expression of inflammatory factors (TNF-α, IL-1β). In contrast, BSHXF restored TGF-β/Smad pathway activity by downregulating miR-199a-3p expression. In vivo experiments demonstrated that miR-199a-3p overexpression exacerbated IDD, characterized by reduced COL2A1 expression, elevated COL1A1 levels, and increased disc fibrosis. BSHXF intervention markedly attenuated IDD progression by downregulating miR-199a-3p expression, reducing disc fibrosis, and effectively restoring collagen expression.

Conclusion

BSHXF activated the TGF-β/Smad pathway to promote the differentiation of ADSCs into nucleus pulposus-like cells. It exerted protective effects by alleviating oxidative stress damage, improving the microenvironment, delaying senescence, and enhancing cellular functions. This study is the first to reveal that miR-199a-3p overexpression exacerbates intervertebral disc fibrosis and degeneration. BSHXF restored TGF-β/Smad pathway activity by downregulating miR-199a-3p expression, thereby improving disc structure and function. This integrated approach offers a novel multi-target intervention strategy for IDD, demonstrating significant therapeutic potential.

Current state of heart failure treatment: are mesenchymal stem cells and their exosomes a future therapy?

Heart failure (HF) represents the terminal stage of cardiovascular disease and remains a leading cause of mortality. Epidemiological studies indicate a high prevalence and mortality rate of HF globally. Current treatment options primarily include pharmacological and non-pharmacological approaches. With the development of mesenchymal stem cell (MSC) transplantation technology, increasing research has shown that stem cell therapy and exosomes derived from these cells hold promise for repairing damaged myocardium and improving cardiac function, becoming a hot topic in clinical treatment for HF. However, this approach also presents certain limitations. This review summarizes the mechanisms of HF, current treatment strategies, and the latest progress in the application of MSCs and their exosomes in HF therapy.

Effectiveness and safety of multiple injections of human placenta-derived MSCs for knee osteoarthritis: a nonrandomized phase I trial

OBJECTIVE

This study investigates the safety and efficacy of three intra-articular (IA) injections of cryopreserved human placenta-derived mesenchymal stem cells (hP-MSCs) for knee osteoarthritis (KOA) over a 1-year follow-up period.

METHODS

A total of 26 patients with stage II-III KOA were enrolled in this non-randomized, open-label study. Patients received either conventional therapy with hyaluronic acid (HA) alone (Control group, n = 11) or in combination with hP-MSCs (MSC group, n = 15) via three intra-articular injections with 4-week intervals. Clinical outcomes were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analogue Scale (VAS), and magnetic resonance imaging (MRI) at 6 and 12 months following the first injection. Blood samples were analyzed for cytokine levels.

RESULTS

Three injections of hP-MSCs combined with HA were well-tolerated, with no severe adverse events observed. Significant improvements in WOMAC and VAS scores were noted in the MSC group compared to the Control group at both 6 and 12 months. MRI analysis revealed no significant differences in cartilage thickness or optical density index between the groups. Additionally, serum cytokine analysis showed a significant decrease in interleukin-2 (IL-2) levels in the MSC group, indicating an anti-inflammatory effect of hP-MSCs. However, no significant changes were observed in other cytokines.

CONCLUSION

This study demonstrates that three intra-articular injections of cryopreserved hP-MSCs in combination with HA are safe and effective for treating KOA, providing sustained clinical improvement at the 1-year follow-up.

TRIAL REGISTRATION

NCT04453111, #7/09.26.2018. Registered 02 January 2020, https://www.

CLINICALTRIALS

gov/study/NCT04453111 .

Evaluating the efficacy of stem cells in treating severe dry eye disease

Dry eye disease (DED) is a multifactorial disorder that disturbs ocular surface equilibrium, considerably diminishing quality of life. Present therapies only offer symptomatic alleviation. Stem cell treatment, especially mesenchymal stem cells (MSCs), has surfaced as a viable approach for tissue regeneration and immunological regulation in DED. Preclinical and early clinical investigations indicate that MSCs can improve lacrimal gland functionality, diminish inflammation, and facilitate corneal regeneration. Nonetheless, obstacles persist in enhancing MSC viability, determining the optimal MSC source, and guaranteeing sustained therapeutic effectiveness. Additional extensive randomized clinical trials are required to confirm the efficacy of MSC-based therapies for severe DED.

Mesenchymal stem cells and their extracellular vesicles: new therapies for cartilage repair

Cartilage is crucial for joints, and its damage can lead to pain and functional impairment, causing financial burden to patients. Due to its weak self-repair, cartilage injury control is a research focus. Cartilage injury naturally with age, but mechanical trauma, lifestyle factors and certain genetic abnormalities can increase the likelihood of symptomatic disease progression. Current treatments for cartilage injury include pharmacological and surgical interventions, but these lack the ability to stop the progression of disease and restore the regeneration of the cartilage. Biological therapies have been evaluated but show varying degrees of efficacy in cartilage regeneration long-term. The mesenchymal stem cell (MSC) therapy attracts attention as it is easily harvested and expanded. Once thought to repair via differentiation, MSCs are now known to secrete extracellular vesicles (EVs) paracrinely. These EVs, rich in bioactive molecules, enable cell communication, boost growth factor secretion, regulate the synthesis and degradation of extracellular matrix (ECM), and modulate inflammation, vital for cartilage repair. However, further research and clinical validation are still required for the application of MSC and MSC-EVs. This review highlights the current state of research on the use of MSC and MSC-EVs in the treatment of cartilage injury. It is hoped that the review in this paper will provide valuable references and inspiration for future researchers in therapeutic studies of cartilage repair.

New mesenchymal stem/stromal cell-based strategies for osteoarthritis treatment: targeting macrophage-mediated inflammation to restore joint homeostasis

Macrophages are pivotal in osteoarthritis (OA) pathogenesis, as their dysregulated polarization can contribute to chronic inflammatory processes. This review explores the molecular and metabolic mechanisms that influence macrophage polarization and identifies potential strategies for OA treatment. Currently, non-surgical treatments for OA focus only on symptom management, and their efficacy is limited; thus, mesenchymal stem/stromal cells (MSCs) have gained attention for their anti-inflammatory and immunomodulatory capabilities. Emerging evidence suggests that small extracellular vesicles (sEVs) derived from MSCs can modulate macrophage function, thus offering potential therapeutic benefits in OA. Additionally, the transfer of mitochondria from MSCs to macrophages has shown promise in enhancing mitochondrial functionality and steering macrophages toward an anti-inflammatory M2-like phenotype. While further research is needed to confirm these findings, MSC-based strategies, including the use of sEVs and mitochondrial transfer, hold great promise for the treatment of OA and other chronic inflammatory diseases.

Continuous collection of human mesenchymal-stromal-cell-derived extracellular vesicles from a stirred tank reactor operated under xenogeneic-free conditions for therapeutic applications

BACKGROUND

Mesenchymal-stromal-cell-derived extracellular vesicles (MSC-EVs) play a key role in the paracrine effects of MSC and have demonstrated therapeutic potential in various preclinical models. However, clinical translation is hindered by manufacturing practices relying on planar culture systems, fetal bovine serum (FBS)-supplemented media, and non-scalable, low-purity EV isolation methods that fail to meet dose and safety requirements, underscoring the need for innovative approaches. In this study, we developed a scalable platform to manufacture human MSC-EVs at clinically relevant numbers, integrating continuous collection of EV-enriched conditioned media (CM) using a stirred-tank reactor (STR) under xenogeneic-free conditions and a scalable downstream process.

METHODS

Wharton's jelly-derived MSC (MSC(WJ)) were expanded using microcarriers in a controlled STR using human platelet lysate (hPL)-supplemented medium. Then, a 3-day EV production stage, featuring continuous harvesting of the CM, was established using a novel serum-/xeno(geneic)-free exosome depleted-hPL supplement. For the isolation of MSC-EVs, a scalable process was implemented by pairing tangential flow filtration and anion exchange chromatography. Isolated MSC-EVs were characterised using nanoparticle tracking analysis, protein and zeta potential quantification, western blot analysis of EV protein markers, transmission electron microscopy and uptake studies of fluorescently labelled-EVs.

RESULTS

The system sustained the efficient expansion of MSC(WJ), reaching a total of (6.03 ± 0.181) x 107 cells after 7 days, which corresponds to a 30.1 ± 0.740-fold expansion. Upon a 3-day continuous CM harvesting, a total of (2.13 ± 0.301) x 1012 EVs were isolated corresponding to a particle yield factor of (1.26 ± 0.186) x 104 EVs/cell/day. MSC-EVs presented high purity levels ((5.53 ± 1.55) x 109 particles/µg), a homogeneous small size distribution (mean diameter of 115 ± 4.88 nm), a surface charge of -23.4 ± 6.23 mV, positive detection of tetraspanins CD9 and CD63 and syntenin-1 and displayed a typical cup-shaped morphology. MSC-EVs were readily incorporated by endothelial cells and two human breast cancer cell lines.

CONCLUSIONS

Overall, the scalable and Good Manufacturing Practices (GMP)-compliant platform established herein enabled the reproducible manufacturing of MSC-EVs with high purity and generally accepted characteristics concerning size, protein markers, surface charge, morphology, and cellular internalization, validating its potential for future clinical applications.

Three-Dimensional Bioprinted Gelatin-Genipin Hydrogels Enriched with hUCMSC-Derived Small Extracellular Vesicles for Regenerative Wound Dressings

Mesenchymal stromal cell-derived small extracellular vesicles (MSC-sEVs) have shown great promise in promoting tissue repair, including skin wound healing, but challenges like rapid degradation and short retention have limited their clinical application. Hydrogels have emerged as effective carriers for sustained EV release. Three-dimensional printing enables the development of personalized skin substitutes tailored to the wound size and shape. This study aimed to develop 3D bioprinted gelatin-genipin hydrogels incorporating human umbilical cord MSC-sEVs (hUCMSC-sEVs) for future skin wound healing applications. Gelatin hydrogels (8% and 10% w/v) were crosslinked with 0.3% genipin (GECL) to improve stability. The hydrogels were evaluated for their suitability for extrusion-based 3D bioprinting and physicochemical properties, such as the swelling ratio, hydrophilicity, enzymatic degradation, and water vapor transmission rate (WVTR). Chemical characterization was performed using EDX, XRD, and FTIR. The hUCMSC-sEVs were isolated via centrifugation and tangential flow filtration (TFF) and characterized. The crosslinked hydrogels were successfully 3D bioprinted and demonstrated superior properties, including high hydrophilicity, a swelling ratio of ~500%, slower degradation, and optimal WVTR. hUCMSC-sEVs, ranging from 50 to 200 nm, were positive for surface and cytosolic markers. Adding 75 μg/mL of hUCMSC-EVs into 10% GECL hydrogels significantly improved the biocompatibility. These hydrogels offer ideal properties for 3D bioprinting and wound healing, demonstrating their potential as biomaterial scaffolds for skin tissue regeneration applications.

An engineered miniACE2 protein secreted by mesenchymal stromal cells effectively neutralizes multiple SARS-CoV- 2 variants in vitro

SARS-CoV- 2 continues to evolve, producing novel Omicron subvariants through recombinant lineages that acquire new mutations, undermining existing antiviral strategies. The viral fitness and adaptive potential of SARS-CoV- 2 present significant challenges to emergency treatments, particularly monoclonal antibodies, which demonstrate reduced efficacy with the emergence of each new variant. Consequently, immunocompromised individuals, who are more susceptible to severe manifestations of COVID- 19 and face heightened risks of critical complications and mortality, remain vulnerable in the absence of effective emergency treatments. To develop translational approaches that can benefit this at-risk population and establish broader therapeutic strategies applicable across variants, we previously designed and engineered in silico miniACE2 decoys (designated BP2, BP9, and BP11). These decoys demonstrated promising efficacy in neutralizing Omicron subvariants. In this study, we leveraged the therapeutic potential of mesenchymal stromal cells (MSCs) for tissue repair and immunomodulation in lung injuries and used these cells as a platform for the secretion of BP2. Our innovative assays, which were conducted with the BP2 protein secreted into the culture supernatant of BP2-MSCs, demonstrated the potential for neutralizing SARS-CoV- 2, including Omicron subvariants. The development of these advanced therapeutic platforms holds significant promise for scalability to effectively mitigate the impact of severe COVID- 19, contributing to broader and more resilient treatment strategies against the evolving landscape of SARS-CoV- 2 variants.

Therapeutic Potential of Local and Systemic Adipose-Derived Mesenchymal Stem Cell Injections in a Rat Model of Experimental Periodontitis: Implications for Cardiac Function

Periodontitis is a common inflammatory disease that not only damages periodontal tissues but also induces systemic effects, including cardiac dysfunction. Mesenchymal stem cells (MSCs) offer regenerative potential due to their ability to differentiate, modulate immune responses, and secrete anti-inflammatory factors. However, the relative efficacy of local versus systemic MSC administration remains unclear. This study evaluated the therapeutic effects of adipose-derived MSCs (AD-MSCs) in a rat model of experimental periodontitis, comparing local and systemic administration. AD-MSCs were characterized based on morphology, surface marker expression, and differentiation potential. Ligature-induced periodontitis was established over 60 days, after which AD-MSCs (1 × 106 cells) were administered either supraperiosteally (local group) or intravenously (systemic group). Periodontal regeneration was assessed through clinical, radiographic, and histopathological analyses, while cardiac function was evaluated using echocardiography and histopathological examinations. Results demonstrated that local AD-MSC administration provided superior therapeutic benefits compared to systemic delivery. Locally administered cells significantly enhanced bone regeneration, reduced inflammation, and improved periodontal tissue architecture. In contrast, systemic administration offered moderate benefits but was less effective in restoring periodontal integrity. Similarly, in the heart, local treatment resulted in greater improvements in systolic function, as indicated by enhanced ejection fraction and fractional shortening, along with reduced myocardial fibrosis. Although systemic administration also provided cardioprotective effects, diastolic dysfunction persisted in both treatment groups. In conclusion, local AD-MSC administration proved more effective in regenerating periodontal tissues and mitigating cardiac dysfunction, highlighting its potential as an optimized therapeutic strategy for periodontitis and its systemic complications.

Adipose-mesenchymal stem cells enhance the formation of auricular cartilage in vitro and in vivo

Patients suffering from microtia have limited treatment options for auricular reconstruction due to donor-site morbidity, complications, and unaesthetic outcome. Therefore, tissue engineering emerged as an alternative therapeutic option. Here, we generated and characterized human auricular cartilage using differentiated human adipose mesenchymal stem cells (hASCs) combined with human auricular chondrocytes. The differentiated hASCs were analysed for their morphology, phenotype, gene, and protein expression of chondrogenic markers, and biochemical composition at different time points in 2D and 3D in vitro. Importantly, we improved conditions for chondrogenic differentiation of hASCs in vitro to enhance their proliferation, survival, and deposition of cartilaginous-matrix proteins. In particular, gene expression analysis revealed an upregulation of cartilage oligomeric matrix protein (COMP) and aggrecan core protein (ACAN) in hASCs using the improved differentiation protocol in vitro. Additionally, we observed that co-seeding of hASCs with chondrocytes in a 1:5 ratio significantly enhanced the de novo auricular cartilage formation in a collagen-I bioink after 8 weeks on immunodeficient rat. In particular, the co-culture resulted in reduced shrinkage, and increased cartilage matrix production as confirmed by GAG deposition in vivo. Our results demonstrate that in co-cultures, hASCs stimulate cartilage formation due to a synergistic effect: hASCs' differentiation into chondrocytes and a trophic effect of hASCs on human auricular chondrocytes. Here we demonstrate the successful use of an hASC-chondrocyte co-culture technique for auricular cartilage tissue engineering in 3D collagen-I bioink. This co-culture approach omits the major drawbacks of traditional cartilage transplantation and thus, represents a fundamental step towards clinical translation.

Age-related mesenchymal stromal cell senescence is associated with progression from MGUS to multiple myeloma

The risk of progression of monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM) increases with advancing age, suggesting that progression may be influenced by age-related changes within the bone marrow (BM) microenvironment. We hypothesise that senescent mesenchymal stromal cells (MSCs), which accumulate in the BM with age, may contribute to MGUS progression to MM. Here, we show that, like BM MSCs from aged non-cancer controls, BM MSCs from both MM and MGUS patients exhibit a senescent phenotype characterised by enlarged, flattened morphology, increased β-galactosidase activity and CDKN2A expression, and decreased proliferation rate compared with BM MSCs from healthy young individuals. While coculture with BM MSCs suppresses the proliferative capacity of MM cell lines in vitro, induction of senescence via irradiation or replicative exhaustion in healthy MSCs relieves this suppression, compared with non-senescent MSCs. This may, in part, be attributable to upregulated expression of the BMP antagonist Gremlin1 in senescent MSCs, which facillitates MM cell proliferation. Notably, the risk of progression to MM was significantly elevated in MGUS patients with increased MSC senescence. Collectively, our data provide evidence that age-related accumulation of senescent MSCs may be a driver of MGUS to MM progression.

Effects of chorionic mesenchymal stromal cells, their conditioned medium, and membrane particles on neutrophil functionality

Mesenchymal stromal cells (MSC) are multipotent cells that can modulate immune cells, affecting macrophages, monocytes, and lymphocytes. Neutrophils are circulating leucocytes responsible for the first line of defense and can assume different phenotypes depending on their environment: N0, the naïve form, N1 (inflammatory), N2 (anti-inflammatory). This study explores the potentially protective roles of chorionic membrane MSCs and their products-conditioned medium and pre-conditioned cMSC-derived membrane microparticles (MP-cMSC)-on neutrophils. Conditioned medium treatment reduced the rate of apoptosis and enhanced the immunosuppressive potential consistent with an anti-inflammatory profile. MP-cMSC are a noteworthy cell-free therapy, consisting of artificially generated circular lipid bilayer structures with no cargo and approximately 200 nm in size. When added to neutrophil culture, MPs increased neutral red uptake, suggesting an enhanced phagocytic activity. In the MSC co-culture group, a reduced rate of apoptosis, increased neutral red uptake, and elevated programed death-ligand 1 (PD-L1) expression were observed. These findings suggest that the distinct effects elicited by conditioned media, microparticles, and co-culture are likely influenced by the specific nature of the interactions involved-whether purely paracrine, mediated through direct cell-to-cell contact, or a combination of both.

Optimization of 3D Extrusion-Printed Particle-Containing Hydrogels for Osteogenic Differentiation

There is a continued increase in demand for novel bone grafting substitutes to reduce reliance on and address challenges associated with allograft and autograft bone grafts. Current synthetic bone grafting substitutes exhibit low mechanical strength and bioactivity, which has inspired the development of novel grafting materials. Accelerating the translation of new bone graft substitutes requires workflows for high-throughput fabrication and analysis of particle-containing models. This study utilized 3D sacrificial printing for the fabrication of reproducible, cellular scaffolds containing tricalcium phosphate (TCP), hydroxyapatite (HA), or natural coral particles. High-throughput analysis of the cellular scaffolds included quantifying cell metabolism, viability, and calcium consumption, as well as nondestructive analysis of collagen accumulation and destructive methods for assessing cell number and morphological changes. Both particle- and non-particle-containing inks sustained cell metabolism with low and decreasing cell death for 7 days post-printing. Collagen staining, scanning electron microscopy imaging, and calcium and collagen quantification suggested that, under osteogenic induction conditions, cells migrated to the surface of the scaffolds and formed a sheet of cells and a collagen-containing extracellular matrix, thereby indicating osteogenic differentiation. The workflow described herein enables the creation of in vitro models to study the osteogenic nature of new bone grafting substitute materials. High-throughput printing combined with non-destructive screening techniques resulted in reduced time, resources, and associated costs and could be applicable to a broader range of cell types.

The presence of stem cells in the human lacrimal drainage system: A proof of principle study

PurposeTo investigate the presence of stem cells within the lacrimal drainage system.MethodsA prospective interventional case series where human lacrimal sac tissue biopsies were obtained from patients undergoing endoscopic dacryocystorhinostomy or a dacryocystectomy surgery at a tertiary care Dacryology Services. Histopathology, immunohistochemistry, and gene expression studies were performed to check the expression of several basic stem/progenitor specific genes - Cd90, Cd105, Cd73, Abcb5, Abcg2, and P63α.ResultsThe lacrimal sac showed positive expression of general stem cell markers (ABCB5, ABCG2, and P63α) and mesenchymal stem cell-specific markers (CD73, CD90, CD105) using transcriptional and immunolocalization studies. Interestingly, CD73 and CD105 double-positive cells and CD73 and CD90 double-positive cells (specific markers for mesenchymal stem cells) were noted in the lacrimal sac stroma and were confirmed not to be vascular endothelial cells.ConclusionThe present study is proof of the principle of the presence of a wide range of stem cell markers within the human lacrimal sac. This study could serve as a foundation for investigating the stem cells and characterizing them further to better understand the lacrimal drainage disorders.

Autophagy inhibition enhances antifibrotic potential of placental mesenchymal stem cells of fetal origin via regulating TGF-β1 mediated protein degradation of HGF

Mesenchymal stem cell (MSC) therapy represents a promising strategy for pulmonary fibrosis (PF) treatment, with hepatocyte growth factor (HGF) serving as a key mediator of MSC-mediated protection. However, the therapeutic efficacy of MSCs is limited by the complex PF microenvironment, and the mechanisms underlying this limitation remain unclear. This study investigates how the PF pathological microenvironment modulates the antifibrotic potential of placental mesenchymal stem cells of fetal origin (fPMSCs) through HGF regulation and elucidates the molecular mechanisms involved. Morphological analysis, flow cytometry, and multilineage differentiation assays were employed to characterize fPMSCs. Transforming growth factor-β1 (TGF-β1) was employed to simulate the PF microenvironment and activate fPMSCs in vitro. ELISA and Western blotting were used to analyze HGF expression, autophagy markers, and Smad signaling. Autophagosome formation was visualized via confocal microscopy and transmission electron microscopy. Co-immunoprecipitation (Co-IP) assays were performed to assess the interaction between p62 and HGF. The antifibrotic function of fPMSCs was further evaluated using a transwell co-culture system with MRC-5 fibroblasts in vitro and a bleomycin-induced PF mouse model in vivo. Phenotypic characterization confirmed that fPMSCs exhibited canonical MSC morphology, expressed CD73/CD90/CD105, lacked CD14/CD34/CD45/HLA-DR, and differentiated into adipogenic, osteogenic, and chondrogenic lineages. TGF-β1 treatment robustly downregulated the antifibrotic capacity, HGF protein expression, and paracrine secretion in fPMSCs. Recombinant HGF enhanced antifibrotic effects, while an HGF-neutralizing antibody abolished them. TGF-β1 induced autophagy in fPMSCs, promoting HGF degradation via p62 interaction and impairing antifibrotic function in vitro and in vivo. Mechanistically, Smad3 phosphorylation mediated the regulation of autophagy and HGF expression in TGF-β1-treated fPMSCs. Our findings demonstrate that TGF-β1 impairs the antifibrotic function of fPMSCs via autophagy-dependent HGF degradation and Smad3 signaling. Conversely, autophagy inhibition restores HGF levels and enhances fPMSCs' therapeutic efficacy in a preclinical PF model. Targeting autophagy inhibition emerges as a promising therapeutic strategy to counteract pulmonary fibrosis.

Npc1 gene mutation impairs multilineage differentiation potential of hepatic telocytes in murine models

OBJECTIVE

To investigate the effect of the Npc1 gene on the biological activity of Telocytes (TCs) in the liver and to provide theoretical support for further research on the biological activity of TCs.

METHODS

Primary liver tissue cultures (TCs) from neonatal Npc1+/+ and Npc1-/- mice were extracted and cultured using an optimized type II collagenase-digestion protocol, and subsequently purified through a differential adhesion method. The growth state of TCs in both Npc1+/+ and Npc1-/- groups was regularly observed under an inverted microscope, and the morphology of TCs under normal growth conditions was documented. The TCs were identified using scanning electron microscopy and immunofluorescence staining. To investigate the impact of the Npc1 gene on the multilineage differentiation potential of TCs, liver TCs from Npc1+/+ and Npc1-/- groups were induced with adipogenic, osteogenic, and cardiomyoblastic differentiation solutions, respectively.

RESULTS

TCs cell surface markers such as co-expression of vimentin/CD34, vimentin/PDGF-α, and vimentin/c-Kit in Npc1+/+ and Npc1-/- groups. "Combined light and scanning electron microscopy revealed that the cellular structure of TCs from Npc1+/+ and Npc1-/- groups was mainly composed of cell bodies and Telopodes (Tps). TCs exhibited small somata with fusiform, stellate, or spindle-shaped nuclei, depending on the number of Tps. The surface of TCs cell membrane was uneven, and there was no difference in morphology between the two groups. TCs had multilineage differentiation potential, and the positive rate of TCs induced in Npc1-/- group was significantly lower than that in the Npc1+/+ group.

CONCLUSION

Our findings demonstrate that NPC1 deficiency markedly attenuates hepatic TCs' multipotency of liver TCs to differentiate into adipocytes, osteoblasts, and cardiocytes, suggesting that NPC1 protein might affect the pluripotency of TCs by regulating the lipid transport pathway. This finding provides novel insights into TC-mediated mechanisms in NPC pathology and lays a theoretical foundation for regenerative medicine strategies targeting TCs.

Footprint-free induced pluripotent stem cells can be successfully differentiated into mesenchymal stromal cells in the feline model

BACKGROUND

Induced pluripotent stem cells (iPSCs) can propagate indefinitely and give rise to every other cell type, rendering them invaluable for disease modelling, drug development research, and usage in regenerative medicine. While feline iPSCs have been described, there are currently no reports on generating genome integration (footprint)-free iPSCs from domestic cats. Therefore, the objective of this study was to generate feline iPSCs from fetal fibroblasts using non-integrative Sendai virus (SeV) vectors carrying human transcription factors. Moreover, these iPSCs were differentiated into mesenchymal stromal cells (MSCs), which can be used as an alternative to tissue-derived MSCs.

METHODS

Feline fetal fibroblasts were transduced with CytoTune-iPS 2.0 Sendai Reprogramming vectors at recommended multiplicity of infections (MOI) and cultured for about 6 days. At 7 days post transduction cells were dissociated, replated on inactivated feeder cells and maintained in iPSC medium for 28 days with daily medium change. Emerging iPSC colonies were mechanically passaged and transferred to fresh feeder cells and further passaged every 6-8 days. Four feline iPSC lines were generated, with two selected for further in-depth characterization. Feline iPSCs were then differentiated into MSCs using a serial plating strategy and an inhibitor of the transforming growth factor-β (TGF-β) type I receptor.

RESULTS

Feline iPSCs exhibited characteristic colony morphology, high nuclear-to-cytoplasmic ratio, positive alkaline phosphatase activity, and expressed feline OCT4, SOX2, and Nanog homeobox (NANOG) stem cell markers. Expression of SeV-derived transgenes decreased during passaging to be eventually lost from the host cells and feline iPSCs could be stably maintained for over 35 passages. Feline iPSCs differentiated into embryoid bodies in vitro and did not form fully differentiated teratomas; instead, they generated in vivo masses containing mesodermal tissue derivatives when injected into immunodeficient mice. Feline iPSC-derived MSCs were plastic adherent, displayed MSC-like morphology, expressed MSC-specific surface markers, and differentiated into cells from the mesodermal lineage in vitro. RNA deep sequencing identified 1,189 differentially expressed genes in feline iPSC-derived MSCs compared to feline iPSCs.

CONCLUSION

We demonstrated the generation of footprint-free iPSCs from domestic cats and their directed differentiation potential towards MSCs. These SeV-derived feline iPSCs and iPSC-derived MSCs will provide valuable models to study feline diseases and explore novel therapeutic strategies and can serve as translational models for human health, leading to increased knowledge on disease pathogenesis and improved therapeutic interventions.

Exploring the role of gut microbiota modulation in the long-term therapeutic benefits of early MSC transplantation in MRL/lpr mice

BACKGROUND

Systemic lupus erythematosus (SLE), influenced by gut microbiota dysbiosis, is characterized by autoimmune and inflammatory responses. Human umbilical cord-derived mesenchymal stem cell (hUC-MSC) transplantation is an effective and safe treatment for refractory or severe SLE; however, the long-term efficacy and mechanisms of early hUC-MSC therapeutic benefits in SLE need further investigation.

METHODS

Here, lupus-prone MRL/MpJ-Faslpr (MRL/lpr) mice were divided into three groups: the control (Ctrl) group received saline injections, while the MSC and MSC-fecal microbiota transplantation (FMT) groups received early hUC-MSC transplants at weeks 6, 8, and 10. The MSC-FMT group also underwent FMT from the Ctrl group between weeks 9 and 13.

RESULTS

Our results showed that early MSC treatment extended therapeutic effects up to 12 weeks, reducing autoantibodies, proinflammatory cytokines, B cells, and improving lupus nephritis. It also modulated the gut microbiota, increasing the abundance of beneficial bacteria, such as Lactobacillus johnsonii and Romboutsia ilealis, which led to higher levels of plasma tryptophan and butyrate metabolites. These metabolites activate the aryl hydrocarbon receptor (AHR), upregulate the Cyp1a1 and Cyp1b1 gene, enhance the zonula occludens 1 (ZO-1) protein, promote intestinal repair, and mitigate SLE progression. Notably, FMT from lupus mice significantly reversed hUC-MSC benefits, suggesting that the modulation of the gut microbiota plays a crucial role in the therapeutic response observed in MRL/lpr mice.

CONCLUSIONS

This research innovatively explores the early therapeutic window for MSCs in SLE, highlighting the partial mechanisms through which hUC-MSCs modulate the gut microbiota-tryptophan-AHR axis, thereby ameliorating SLE symptoms.

Enhancing the Therapeutic Potential of Human Umbilical Cord Mesenchymal Stem Cells for Osteoarthritis: The Role of Platelet-Rich Plasma and Extracellular Vesicles

Osteoarthritis (OA) is a chronic degenerative joint disease. Our previous study demonstrated that extracellular vesicles (EVs) secreted by human umbilical cord mesenchymal stem cells (HUCMSCs), which play a crucial role in regenerative medicine, have therapeutic effects on OA. Additionally, platelet-rich plasma (PRP) has been widely used in musculoskeletal diseases as it promotes wound healing, angiogenesis, and tissue remodeling; however, its efficacy as a stand-alone therapy remains controversial. Therefore, we investigated the therapeutic effects of combining stem cell-derived EVs with PRP in an OA model. HUCMSC-derived EVs treated with PRP were used as the experimental group, whereas HUCMSC-derived EVs cultured with serum-free (SF) or exosome-depleted fetal bovine serum (exo(-)FBS) and PRP served as controls. PRP-treated HUCMSCs maintained their surface antigen characteristics and potential to differentiate into adipocytes, osteoblasts, and chondrocytes. In the OA model, mice treated with HUCMSCs + 5% PRP-derived EVs showed significantly improved motor function compared to controls and were comparable to those treated with HUCMSCs +SF and +exo(-)FBS-derived EVs. Additionally, increased type II collagen and aggrecan and decreased IL-1β expression were observed in cartilage transplanted with various EVs. In conclusion, PRP enhances HUCMSC differentiation, whereas treatment with EVs improves OA outcomes, providing a promising strategy for future clinical applications.

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

The impact of the inflammatory pulmonary microenvironment on the behavior and function of mesenchymal stromal cells

INTRODUCTION

Acute respiratory distress syndrome is characterized by the dysregulation and activation of several inflammatory pathways which lead to widespread inflammation in the lungs. Presently, direct therapy is unavailable and the use of mesenchymal stromal cells as a direct therapy has been proposed, as early-phase studies have shown promise.

AREAS COVERED

MSCs exert various therapeutic effects on the inflammatory microenvironment, such as anti-microbial effects, restoration of the alveolar-capillary barrier, and exuding various anti-inflammatory effects. However, to exert these effects MSCs need to be submitted to specific external stimuli which can affect their immunomodulation, survival, migration and metabolic state. This review references several articles found through targeted searches in PubMed [Accessed between November 2024 and March 2025], for key terms such as 'mesenchymal stromal cells', 'inflammatory microenvironment', anti-inflammatory', 'metabolism', and 'immunomodulation'.

EXPERT OPINION

The advancement of MSCs therapy in the treatment of ARDS has not progressed as effectively as one might have anticipated. Several clinical findings have established patient subgroups based on inflammatory cytokine profiles and severity of ARDS. This variation in patients may influence the clinical efficacy of MSCs and instead of concluding that MSCs therapy is not worth pursuing, more research is needed to develop an appropriate therapy.

Recent Advances in Modeling Tissues Using 3D Bioprinted Nanocellulose Bioinks

Bioprinting creates 3D tissue models by depositing cells encapsulated in biocompatible materials. These 3D printed models can better emulate physiological conditions in comparison with traditional 2D cell cultures or animal models. Such models can be produced from human cells, possessing human genetics and replicating the 3D microenvironment found in vivo. Many different types of biocompatible materials serve as bioinks, including gelatin methacryloyl (GelMA), alginate, fibrin, and gelatin. Nanocellulose has emerged as a promising addition to these materials. Nanocellulose─composed of cellulose chain bundles with lateral dimensions ranging from a few to several tens of nanometers─possesses key properties for 3D bioprinting applications. It can form biocompatible hydrogels, which have excellent physical properties, and its structure resembles collagen, making it useful for modeling tissues with high collagen content such as bone, cartilage, sink, and muscle. Here we review some of the recent advances in the use of nanocellulose in bioinks for the creation of bone, cartilage, skin, and muscle tissue specific models and identify areas for future progress.

Establishing a Bioink Assessment Protocol: GelMA and Collagen in the Bioprinting of a Potential In Vitro Intestinal Model

Collagen and gelatin methacryloyl (GelMA) are widely studied biomaterials for extrusion-based bioprinting (EBB) due to their excellent biological properties and ability to mimic the extracellular matrix of native tissues. This study aims to establish a preliminary workflow for approaching EBB by assessing collagen and GelMA printability and biological performance. GelMA was selected for its cost-effectiveness and ease of synthesis, while our collagen formulation was specifically optimized for printability, which is a challenging aspect of bioprinting. A parallel evaluation of their printability and biological performance is provided to develop a preliminary 3D intestinal model replicating the submucosa, lamina propria, and epithelial layer. Rheological analyses demonstrated that both materials exhibit a shear-thinning behavior. Collagen (u-CI) displayed a shear-thinning parameter p = 0.1 and a consistency index C = 80.62 Pa·s, while GelMA (u-GI) exhibited a more pronounced shear-thinning effect and enhanced shape retention (p = 0.06, C = 286.6 Pa·s). Post-extrusion recovery was higher for collagen (85%), compared to GelMA (45%), indicating its greater mechanical resilience. Photo-crosslinking improved hydrogel stability, with an increase in storage modulus G' for both materials. Printing tests confirmed the suitability of both hydrogels for bioprinting, with GelMA demonstrating higher print fidelity than collagen. Dimensional stability assessments under incubating conditions revealed that collagen constructs maintained their shape for 14 days before degradation, whereas GelMA constructs exhibited a gradual decrease in diameter over 21 days. Cell culture studies showed that human skin fibroblasts (HSFs) and human colon adenocarcinoma cells (HCT-8) could be successfully cocultured in an optimized RPMI 1640-based medium. AlamarBlue assays and Live/Dead staining confirmed high cell viability and proliferation within both hydrogel matrices. Notably, HSFs in GelMA exhibited more elongated morphologies, likely due to the material's lower stiffness (380 Pa) compared to collagen (585 Pa). HCT-8 cells adhered more rapidly to GelMA constructs, forming colonies within 7 days, whereas on collagen, colony formation was delayed to 14 days. Finally, a layered intestinal model was fabricated, and immunostaining confirmed the expression of tight junction (ZO-1) and adhesion (E-cadherin) proteins, validating the epithelial monolayer integrity. These findings highlight the potential of collagen and GelMA in 3D bioprinting applications for gut tissue engineering and pave the way for future developments of in vitro intestinal models.

The influence of cell source on the senescence of human mesenchymal stem/stromal cells

While mesenchymal stem/stromal cells (MSCs) exhibit the ability to self-renew, they are not immortal; they eventually reach a point of irreversible growth cessation and functional deterioration following a limited series of population doublings, referred to as replicative senescence. When evaluated according to the criteria set by the International Society for Cell Therapy (ISCT), MSCs show significant differences in their senescence patterns and other characteristics related to their phenotype and function. These differences are attributed to the source of the MSCs and the conditions in which they are grown. MSCs derived from fetal or adult sources have variations in their genome stability, as well as in the expression and epigenetic profile of the cells, which in turn affects their secretome. Understanding the key factors of MSC senescence based on cell source can help to develop effective strategies for regulating senescence and improving the therapeutic potential.