Human mesenchymal stem cells generate a distinct pericellular zone of MMP activities via binding of MMPs and secretion of high levels of TIMPs

Intramyocardial injection of pre-cultured endothelial progenitor cells and mesenchymal stem cells inside alginate/gelatin microspheres induced angiogenesis in infarcted rabbits

Background

Using several strategies, the stimulation of angiogenesis can alleviate the pathological complications of post-myocardial ischemia. Here, endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) were pre-cultured inside the alginate/gelatin (Alg/Gel) microspheres in the presence of SDF-1α for 7 days, and their angiogenesis potential was monitored in infarcted rabbits.

Methods

The decapsulated cells were monitored in terms of cell dynamic growth and angiogenesis potential in vitro and after injection into ischemic myocardium in rabbits.

Results

Based on the data, 7-day incubation inside the Alg/Gel microspheres led to the stimulation of angiogenesis profile (Ang-1↑, -2↑, Tie-2↑), migration (MMP-2↑, and − 9↑), and autophagic response (Beclin-1↑, LC3↑, and p-62↓) in EPCs containing groups in the presence of SDF-1α. PCR array analysis revealed the expression of angiogenesis-related genes in the presence of SDF-1α. These features coincided with the stimulation of in vitro tubulogenesis properties in EPCs and EPCs + SDF-1α groups. The injection of cells from different groups into the infarcted rabbits led to the reduction of fibrotic area in ischemic myocardium in MSCs-bearing groups, and these effects were intensified in the presence of SDF-1α. Pre-treatment of EPCs and MSCs increased the recruited immune cells into the ischemic area within the myocardium. It was suggested that SDF-1α stimulated the local vascular density (CD31 capillaries, and α-SMA arterioles) in EPCs-bearing groups compared to MSCs and MSCs + SDF-1α groups.

Conclusions

These data indicate that pre-culture of EPCs and MSCs inside the Alg-based hydrogels can increase the regenerative potential of these cells, especially when exposed to stimulatory cytokines such as SDF-1α for the alleviation of ischemic changes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12964-025-02301-0.

Reciprocal Modulation of Tumour and Immune Cell Motility: Uncovering Dynamic Interplays and Therapeutic Approaches

Dysregulated cell movement is a hallmark of cancer progression and metastasis, the leading cause of cancer-related mortality. The metastatic cascade involves tumour cell migration, invasion, intravasation, dissemination, and colonisation of distant organs. These processes are influenced by reciprocal interactions between cancer cells and the tumour microenvironment (TME), including immune cells, stromal components, and extracellular matrix proteins. The epithelial-mesenchymal transition (EMT) plays a crucial role in providing cancer cells with invasive and stem-like properties, promoting dissemination and resistance to apoptosis. Conversely, the mesenchymal-epithelial transition (MET) facilitates metastatic colonisation and tumour re-initiation. Immune cells within the TME contribute to either anti-tumour response or immune evasion. These cells secrete cytokines, chemokines, and growth factors that shape the immune landscape and influence responses to immunotherapy. Notably, immune checkpoint blockade (ICB) has transformed cancer treatment, yet its efficacy is often dictated by the immune composition of the tumour site. Elucidating the molecular cross-talk between immune and cancer cells, identifying predictive biomarkers for ICB response, and developing strategies to convert cold tumours into immune-active environments is critical to overcoming resistance to immunotherapy and improving patient survival.

Extracellular Signaling Molecules from Adipose-Derived Stem Cells and Ovarian Cancer Cells Induce a Hybrid Epithelial-Mesenchymal Phenotype in a Bidirectional Interaction

Ovarian cancer (OC) is characterized by high mortality rates due to late diagnosis, recurrence, and metastasis. Here, we show that extracellular signaling molecules secreted by adipose-derived mesenchymal stem cells (ASCs) and OC cells-either in the conditioned medium (CM) or within small extracellular vesicles (sEVs)-modulate cellular responses and drive OC progression. ASC-derived sEVs and CM secretome promoted OC cell colony formation, invasion, and migration while upregulating tumor-associated signaling pathways, including TGFβ/Smad, p38MAPK/ERK1/2, Wnt/β-catenin, and MMP-9. Additionally, OC-derived sEVs and CM induced a pro-tumorigenic phenotype in ASCs, enhancing their invasiveness and expression of tumor-associated factors. Notably, both ASCs and OC cells exhibited increased expression of E-cadherin and Snail/Slug proteins, key markers of epithelial/mesenchymal hybrid phenotype, enhancing cellular plasticity and metastatic potential. We also demonstrated that these cellular features are, at least in part, due to the presence of tumor-supportive molecules such as TNF-α, Tenascin-C, MMP-2, and SDF-1α in the CM secretome of ASCs and OC cells. In silico analyses linked these molecular changes to poor prognostic outcomes in OC patients. These findings highlight the critical role of sEVs and tumor/stem cell-derived secretome in OC progression through bidirectional interactions that impact cellular behavior and phenotypic transitions. We suggest that targeting EV-mediated communication could improve therapeutic strategies and patient outcomes.

The Potential of Mesenchymal Stem/Stromal Cells in Diabetic Wounds and Future Directions for Research and Therapy-Is It Time for Use in Everyday Practice?

The treatment of diabetic wounds is impaired by the intricate nature of diabetes and its associated complications, necessitating novel strategies. The utilization of mesenchymal stem/stromal cells (MSCs) as a therapeutic modality for chronic and recalcitrant wounds in diabetic patients is an active area of investigation aimed at enhancing its therapeutic potential covering tissue regeneration. The threat posed to the patient and their environment by the presence of a diabetic foot ulcer (DFU) is so significant that any additional therapeutic approach that opens new pathways to halt the progression of local changes, which subsequently lead to a generalized inflammatory process, offers a chance to reduce the risk of amputation or even death. This article explores the potential of MSCs in diabetic foot ulcer treatment, examining their mechanisms of action, clinical application challenges, and future directions for research and therapy.

Mesenchymal stromal cells as cancer promoters

Mesenchymal stromal cells (MSCs) are important cellular constituents of tumor stroma that play an active role in tumor development. Complex interactions between MSCs and cancer promote tumor progression by creating a favorable milieu for tumor cell proliferation, angiogenesis, motility, invasion, and metastasis. The cellular heterogeneity, source of origin, diversity in isolation methods, culture techniques and model systems of MSCs, together with the different tumor subtypes, add to the complexity of MSC-tumor interactions. In this review, we discuss the mechanisms of MSC-mediated tumor promotion and evaluate cell-stromal interactions between cancer cells, MSCs, cells of the tumor microenvironment (TME), and the extracellular matrix (ECM). A more thorough understanding of tumor-MSC interactions is likely to lead to better cancer management.

Human adipose and umbilical cord mesenchymal stem cell-derived extracellular vesicles mitigate photoaging via TIMP1/Notch1

UVB radiation induces oxidative stress, DNA damage, and inflammation, leading to skin wrinkling, compromised barrier function, and an increased risk of carcinogenesis. Addressing or preventing photoaging may offer a promising therapeutic avenue for these conditions. Recent research indicated that mesenchymal stem cells (MSCs) exhibit significant therapeutic potential for various skin diseases. Given that extracellular vesicles (EV) can deliver diverse cargo to recipient cells and elicit similar therapeutic effects, we investigated the roles and underlying mechanisms of both adipose-derived MSC-derived EV (AMSC-EV) and umbilical cord-derived MSC-derived EV (HUMSC-EV) in photoaging. Our findings indicated that in vivo, treatment with AMSC-EV and HUMSC-EV resulted in improvements in wrinkles and skin hydration while also mitigating skin inflammation and thickness alterations in both the epidermis and dermis. Additionally, in vitro studies using human keratinocytes (HaCaTs), human dermal fibroblast cells (HDFs), and T-Skin models revealed that AMSC-EV and HUMSC-EV attenuated senescence, reduced levels of reactive oxygen species (ROS) and DNA damage, and alleviated inflammation induced by UVB. Furthermore, EV treatment enhanced cell viability and migration capacity in the epidermis and promoted extracellular matrix (ECM) remodeling in the dermis in photoaged cell models. Mechanistically, proteomics results showed that TIMP1 was highly expressed in both AMSC-EV and HUMSC-EV and could exert similar effects as MSC-EV. In addition, we found that EV and TIMP1 could inhibit Notch1 and downstream targets Hes1, P16, P21, and P53. Collectively, our data suggests that both AMSC-EV and HUMSC-EV attenuate skin photoaging through TIMP1/Notch1.

The Therapeutic Potential of Adipose-Derived Mesenchymal Stem Cell Secretome in Osteoarthritis: A Comprehensive Study

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. This study investigates the therapeutic potential of secretome derived from adipose tissue mesenchymal stem cells (ASCs) in mitigating inflammation and promoting cartilage repair in an in vitro model of OA. Our in vitro model comprised chondrocytes inflamed with TNF. To assess the therapeutic potential of secretome, inflamed chondrocytes were treated with it and concentrations of pro-inflammatory cytokines, metalloproteinases (MMPs) and extracellular matrix markers were measured. In addition, secretome-treated chondrocytes were subject to a microarray analysis to determine which genes were upregulated and which were downregulated. Treating TNF-inflamed chondrocytes with secretome in vitro inhibits the NF-κB pathway, thereby mediating anti-inflammatory and anti-catabolic effects. Additional protective effects of secretome on cartilage are revealed in the inhibition of hypertrophy markers such as RUNX2 and COL10A1, increased production of COL2A1 and ACAN and upregulation of SOX9. These findings suggest that ASC-derived secretome can effectively reduce inflammation, promote cartilage repair, and maintain chondrocyte phenotype. This study highlights the potential of ASC-derived secretome as a novel, non-cell-based therapeutic approach for OA, offering a promising alternative to current treatments by targeting inflammation and cartilage repair mechanisms.

Immune and non-immune mediators in the fibrosis pathogenesis of salivary gland in Sjögren's syndrome

Sjögren's syndrome (SS) or Sjögren's disease (SjD) is a systemic autoimmune disease clinically manifested as sicca symptoms. This disease primarily impacts the functionality of exocrine glands, specifically the lacrimal and salivary glands (SG). SG fibrosis, an irreversible morphological change, is a severe consequence that occurs in the later stages of the disease due to sustained inflammation. However, the mechanism underlying SG fibrosis in SS remains under-investigated. Glandular fibrosis may arise from chronic sialadenitis, in which the interactions between infiltrating lymphocytes and epithelial cells potentially contributes to fibrotic pathogenesis. Thus, both immune and non-immune cells are closely involved in this process, while their interplays are not fully understood. The molecular mechanism of tissue fibrosis is partly associated with an imbalance of immune responses, in which the transforming growth factor-beta (TGF-β)-dependent epithelial-mesenchymal transition (EMT) and extracellular matrix remodeling are recently investigated. In addition, viral infection has been implicated in the pathogenesis of SS. Viral-specific innate immune response could exacerbate the autoimmune progression, resulting in overt inflammation in SG. Notably, post-COVID patients exhibit typical SS symptoms and severe inflammatory sialadenitis, which are positively correlated with SG damage. In this review, we discuss the immune and non-immune risk factors in SG fibrosis and summarize the evidence to understand the mechanisms upon autoimmune progression in SS.

Combination of mesenchymal stem cell sheet with poly-caprolactone nanofibrous mat and Gelfoam increased osteogenesis capacity in rat calvarial defect

Introduction

To date, different strategies have been used for co-transplantation of cell-loaded biomaterials for bone tissue regeneration. This study aimed to investigate the osteogenic properties of adipose-derived-mesenchymal stem cell (AD-MSC) sheets combined with nanofibrous poly-caprolactone (PCL) mat and Gelfoam in rats with calvarial bone defect.

Methods

Calvarial critical-size defects were induced in male rats. Animals were classified into Control, Gelfoam, Gelfoam/PCL nanofiber, Gelfoam/AD-MSC sheet, and Gelfoam/PCL nanofiber/AD-MSC sheet groups. After 3 months, rats were sacrificed and the regeneration rate was evaluated.

Results

Almost all groups showed bone regeneration properties, but the volume of newly formed bone was higher in groups that received Gelfoam/AD-MSC and Gelfoam/PCL nanofiber/AD-MSC sheets (P < 0.05). The application of Gelfoam/PCL nanofiber/AD-MSC sheets not only increased bone thickness, bone volume/total bone volume (BV/TV) ratio, strong Hounsfield Unit (HU), but also led to the formation of ossified connective tissue with wrinkled patterns.

Conclusion

The current study indicated that the Gelfoam/PCL nanofiber/AD-MSC sheet provides a suitable platform for effective osteogenesis in calvarial bone defects.

Mesenchymal stem cell-derived exosomes as a promising cell-free therapy for knee osteoarthritis

Osteoarthritis (OA), as a degenerative disease, leads to high socioeconomic burdens and disability rates. The knee joint is typically the most affected and is characterized by progressive destruction of articular cartilage, subchondral bone remodeling, osteophyte formation and synovial inflammation. The current management of OA mainly focuses on symptomatic relief and does not help to slow down the advancement of disease. Recently, mesenchymal stem cells (MSCs) and their exosomes have garnered significant attention in regenerative therapy and tissue engineering areas. Preclinical studies have demonstrated that MSC-derived exosomes (MSC-Exos), as bioactive factor carriers, have promising results in cell-free therapy of OA. This study reviewed the application of various MSC-Exos for the OA treatment, along with exploring the potential underlying mechanisms. Moreover, current strategies and future perspectives for the utilization of engineered MSC-Exos, alongside their associated challenges, were also discussed.

Immunomodulatory differences between mesenchymal stem cells from different oral tissues

Mesenchymal stem cells (MSCs) have recently been identified as having potentially therapeutic immunomodulatory properties. MSCs isolated from different oral tissues have similar morphology and immunophenotypes, however, direct comparisons of their gene expression and immunomodulatory properties have not been conducted. We isolated alveolar bone-derived MSCs (aBMSCs), dental pulp stem cells (DPSCs) and gingiva-derived MSCs (GMSCs) from the same patients and compared their immunophenotypes and transcriptomes. Additionally, we compared their production of soluble immunomodulatory cytokines as well as their immunoregulatory properties in coculture with THP-1 human monocytic cells. RNA sequencing revealed distinct gene expression in DPSCs while aBMSCs and GMSCs had less differentially expressed genes. DPSCs also had significantly less secretion of osteopontin compared to aBMSCs and GMSCs. Finally, DPSCs did not exhibit an immunosuppresive effect on THP-1 cells to the same degree as aBMSCs and GMSCs. These findings demonstrate that MSCs from different oral tissues have distinct transcriptomes and immunoregulatory properties.

Extracellular matrix turnover in salivary gland disorders and regenerative therapies: Obstacles and opportunities

Salivary gland (SG) extracellular matrix (ECM) has a major influence on tissue development, homeostasis, and tissue regeneration after injury. During aging, disease, and physical insult, normal remodeling of the SG microenvironment (i.e. ECM) becomes dysregulated, leading to alterations in matrix composition which disrupt tissue architecture/structure, alter cell activity, and negatively impact gland function. Matrix metalloproteinases (MMPs) are a large and diverse family of metalloendopeptidases which play a major role in matrix degradation and are intimately involved in regulating development and cell function; dysregulation of these enzymes leads to the production of a fibrotic matrix. In the SG this altered fibrotic ECM (or cell microenvironment) negatively impacts normal cell function and the effectiveness of gene and stem cell therapies which serve as a foundation for many SG regenerative therapies. For this reason, prospective regenerative strategies should prioritize the maintenance and/or restoration of a healthy SG ECM. Mesenchymal stem cells (MSCs) have great potential for mitigating damage to the SG microenvironment by ameliorating inflammation, reducing fibrosis, and repairing the damaged milieu of extracellular regulatory cues, including the matrix. This review addresses our current understanding of the impact of aging and disease on the SG microenvironment and suggests critical deficiencies and opportunities in ECM-targeted therapeutic interventions.

An in vitro culture platform to study the extracellular matrix remodeling potential of human mesenchymal stem cells

The ability of mesenchymal stem cells (MSCs) to synthesize and degrade extracellular matrix (ECM) is important for MSC-based therapies. However, the therapeutic effects associated with ECM remodeling in cultured MSCs have been limited by the lack of a method to assess the ability of cultured cells to degrade ECM in vitro. Here, we describe a simple in vitro culture platform for studying the ECM remodeling potential of cultured MSCs using a high-density collagen (CL) surface. Cells on the CL surface have remarkable ability to degrade collagen fibrils by secreting matrix metalloproteinase (MMP); to study this, the marker collagen hybridizing peptide (CHP) was used. Confirming the ECM remodeling potential of MSCs with different population doublings (PDs), young and healthy γ-H2AX-negative cells, a marker of DNA damage and senescence, showed more extensive collagen degradation on the CL surface, whereas damaged cells of γ-H2AX-positive cells showed no collagen degradation. The frequency of γ-H2AX-/CHP + cells at PD = 0 was 49%, which was 4.9-fold higher than that at PD=13.07, whereas the frequency of γ-H2AX+/CHP- at PD=13.07 was 50%, which was 6.4-folds higher than that at PD=0. Further experimentation examining the in vitro priming effect of MSCs with the pro-inflammatory cytokine interferon-γ treatment showed increased frequency of cells with ECM remodeling potential with higher MMP secretion. Thus, this culture surface can be used for studying the ECM remodeling capacity of ex vivo-expanded MSCs in vitro and may serve as a platform for prediction in vivo ECM remodeling effect. STATEMENT OF SIGNIFICANCE: The extracellular matrix (ECM) remodeling potential of cultured mesenchymal stem cells (MSCs) is important for assessing the effectiveness of MSC-based therapy. However, methods to assess the ability of cultured cells to degrade ECM in vitro are still lacking. Here, we developed a simple in vitro culture platform to study the ECM remodeling potential of cultured MSCs using high-density collagen surfaces. This platform was used to evaluate the ECM remodeling potential of long-term ex vivo-expanded MSCs in vitro.

Stem cell biotherapy: A new remedy for Trichinella spiralis-induced inflammatory myopathy

Trichinella spiralis (T. spiralis)-induced myopathy is an inflammatory myopathy that is difficult to treat unless the parasite is combated in its early intestinal phase before it reaches the muscles. This study aimed to evaluate the effect of local mesenchymal stem cell (MSC) therapy on T. spiralis-induced inflammatory myopathy in rats. Rats were divided into four groups: Group 1 (non-infected non-treated group); Group 2 (infected non-treated group); Group 3 (infected albendazole (ABZ)-treated group); and Group 4 (infected MSC-treated group). Their muscle status was assessed physiologically with the righting reflex and electromyography (EMG), parasitologically with the total muscle larval count, histopathologically with hematoxylin and eosin and Mallory's trichrome stains, as well as immunohistochemically for myogenin as a marker of muscle regeneration. Additionally, serum muscle enzymes creatine kinase (CK) and lactate dehydrogenase (LDH), as well as muscle matrix metalloproteinases MMP1 and MMP9, were assayed. Finally, the immunological response was assessed by measuring the levels of the muscle inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), and interleukin-4 (IL-4). Our findings revealed that MSC therapy markedly improved muscle EMG and righting reflex, as well as the histopathological appearance of the muscles, reduced inflammatory cellular infiltrates, and increased myogenin immunostaining. It also reduced serum CK and LDH levels, as well as muscle INF-γ, TNF-α, IL-4, MMP1, and MMP9 levels. However, it had no effect on the total muscle larval count. Accordingly, due to its anti-inflammatory properties and muscle-regenerative effect, MSC therapy could be a promising new remedy for T. spiralis-induced myopathy.

Autologous mesenchymal stem cells offer a new paradigm for salivary gland regeneration

Salivary gland (SG) dysfunction, due to radiotherapy, disease, or aging, is a clinical manifestation that has the potential to cause severe oral and/or systemic diseases and compromise quality of life. Currently, the standard-of-care for this condition remains palliative. A variety of approaches have been employed to restore saliva production, but they have largely failed due to damage to both secretory cells and the extracellular matrix (niche). Transplantation of allogeneic cells from healthy donors has been suggested as a potential solution, but no definitive population of SG stem cells, capable of regenerating the gland, has been identified. Alternatively, mesenchymal stem cells (MSCs) are abundant, well characterized, and during SG development/homeostasis engage in signaling crosstalk with the SG epithelium. Further, the trans-differentiation potential of these cells and their ability to regenerate SG tissues have been demonstrated. However, recent findings suggest that the "immuno-privileged" status of allogeneic adult MSCs may not reflect their status post-transplantation. In contrast, autologous MSCs can be recovered from healthy tissues and do not present a challenge to the recipient's immune system. With recent advances in our ability to expand MSCs in vitro on tissue-specific matrices, autologous MSCs may offer a new therapeutic paradigm for restoration of SG function.

Development and characterization of Factor Xa-responsive materials for applications in cell culture and biologics delivery

Stimuli-responsive biomaterials may be used to better control the release of bioactive molecules or cells for applications involving drug delivery and controlled cell release. In this study, we developed a Factor Xa (FXa)-responsive biomaterial capable of controlled release of pharmaceutical agents and cells from in vitro culture. FXa-cleavable substrates were formed as hydrogels that degraded in response to FXa enzyme over several hours. Hydrogels were shown to release both heparin and a model protein in response to FXa. Additionally, RGD-functionalized FXa-degradable hydrogels were used to culture mesenchymal stromal cells (MSCs), enabling FXa-mediated cell dissociation from hydrogels in a manner that preserved multicellular structures. Harvesting MSCs using FXa-mediated dissociation did not influence their differentiation capacity or indoleamine 2,3-dioxygenase (IDO) activity (a measure of immunomodulatory capacity). In all, this FXa-degradable hydrogel is a novel responsive biomaterial system that may be used for on-demand drug delivery, as well as for improving processes for in vitro culture of therapeutic cells.

A multifunctional sateen woven dressings for treatment of skin injuries

Cutaneous wounds with impaired healing such as diabetic ulcers and burns constitute major and rapidly growing threat to healthcare systems worldwide. Accelerating wound healing requires the delivery of biological factors that induce angiogenesis, support cellular proliferation, and modulate inflammation while minimizing infection. In this study, we engineered a dressing made by weaving of composite fibers (CFs) carrying mesenchymal stem cells (MSCs) and a model antibiotic using a scalable sateen textile technique. In this regard, two different sets of CFs carrying MSCs or an antimicrobial agent were used to generate a multifunctional dressing. According to cell viability and metabolic activity as CCK-8 and live/dead with qRT-PCR results, more than %90 the encapsulated MSCs remain viable for 28 days and their expression levels of the wound repair factors including ECM remodeling, angiogenesis and immunomodulatory maintained in MSCs post dressing manufacturing for 14 days. Post 10 days culture of the dressing, MSCs within CFs had 10-fold higher collagen synthesis (p < 0.0001) determined by hydroxyproline assay which indicates the enhanced healing properties. According to in vitro antimicrobial activity results determined by disk diffusion and broth microdilution tests, the first day and the total amount of release gentamicin loaded dressing samples during the 28 days were higher than determined minimal inhibition concentration (MIC) values for S. aureus and K. pneumonia without negatively impacting the viability and functionality of encapsulated MSCs within the dressing. The dressing is also flexible and can conform to skin curvatures making the dressing suitable for the treatment of different skin injuries such as burns and diabetic ulcers.

Fat Graft Retention: Adipose Tissue, Adipose-Derived Stem Cells, and Aging

SUMMARY

Over the past 30 years, there has been a dramatic increase in the use of autologous fat grafting for soft-tissue augmentation and to improve facial skin quality. Several studies have highlighted the impact of aging on adipose tissue, leading to a decrease of adipose tissue volume and preadipocyte proliferation and increase of fibrosis. Recently, there has been a rising interest in adipose tissue components, including adipose-derived stem/stromal cells (ASCs) because of their regenerative potential, including inflammation, fibrosis, and vascularization modulation. Because of their differentiation potential and paracrine function, ASCs have been largely used for fat grafting procedures, as they are described to be a key component in fat graft survival. However, many parameters as surgical procedures or adipose tissue biology could change clinical outcomes. Variation on fat grafting methods have led to numerous inconsistent clinical outcomes. Donor-to-donor variation could also be imputed to ASCs, tissue inflammatory state, or tissue origin. In this review, the authors aim to analyze (1) the parameters involved in graft survival, and (2) the effect of aging on adipose tissue components, especially ASCs, that could lead to a decrease of skin regeneration and fat graft retention.

CLINICAL RELEVANCE STATEMENT

This review aims to enlighten surgeons about known parameters that could play a role in fat graft survival. ASCs and their potential mechanism of action in regenerative medicine are more specifically described.

Intra-Articular Injections of the Adipose-Derived Mesenchymal Stem Cells Suppress Progression of a Mouse Traumatic Knee Osteoarthritis Model

OBJECTIVE

This study aimed to determine whether the intra-articular injection of human adipose-derived mesenchymal stem cells (ADSCs) protects against the progression of murine post-traumatic osteoarthritis.

DESIGN

ADSCs were isolated from human abdomen or buttock adipose tissues. In in vitro study, ADSCs conditioned medium was added to human chondrocytes pre-treated with interleukin-1β (IL-1β), and resultant gene expression of target inflammatory genes was measured by real-time quantitative polymerase chain reaction. A mouse model of knee osteoarthritis was generated by unilaterally transecting the medial meniscus in the right hind limb of 20 female C57BL/6 mice. Mice were randomly assigned to 2 treatment groups that received 6 µl intra-articular injections of either phosphate-buffered saline (control) or 2 × 10⁴ cells/μl of ADSCs 14, 28, and 42 days post-surgery. Mice were euthanized 84 days post-surgery and histological and micro-computed tomography evaluation of knee joints were analyzed. Hind limb weight-bearing distribution was measured pre-surgery and 28 and 84 days post-surgery.

RESULTS

Conditioned medium from cultured human adipose-derived mesenchymal stem cells suppressed the expression of target inflammatory genes in chondrocytes pre-treated with IL-1β, suggesting anti-inflammatory properties (P < 0.01). Histological analyses indicated that the progression of destabilization of medial meniscus-induced knee osteoarthritis was suppressed by the administration of ADSCs compared with control group at medial femorotibial joint in vivo. This protective effect was related to a reduction in articular cartilage loss.

CONCLUSION

The intra-articular injection of ADSCs suppressed articular cartilage loss in a mouse model of knee osteoarthritis, possible through anti-inflammatory mechanisms.

Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells, Obesity and the Tumor Microenvironment of Breast Cancer

Breast cancer is the most frequently diagnosed cancer and a common cause of cancer-related death in women. It is well recognized that obesity is associated with an enhanced risk of more aggressive breast cancer as well as reduced patient survival. Adipose tissue is the major microenvironment of breast cancer. Obesity changes the composition, structure, and function of adipose tissue, which is associated with inflammation and metabolic dysfunction. Interestingly, adipose tissue is rich in ASCs/MSCs, and obesity alters the properties and functions of these cells. As a key component of the mammary stroma, ASCs play essential roles in the breast cancer microenvironment. The crosstalk between ASCs and breast cancer cells is multilateral and can occur both directly through cell-cell contact and indirectly via the secretome released by ASC/MSC, which is considered to be the main effector of their supportive, angiogenic, and immunomodulatory functions. In this narrative review, we aim to address the impact of obesity on ASCs/MSCs, summarize the current knowledge regarding the potential pathological roles of ASCs/MSCs in the development of breast cancer, discuss related molecular mechanisms, underline the possible clinical significance, and highlight related research perspectives. In particular, we underscore the roles of ASCs/MSCs in breast cancer cell progression, including proliferation and survival, angiogenesis, migration and invasion, the epithelial-mesenchymal transition, cancer stem cell development, immune evasion, therapy resistance, and the potential impact of breast cancer cells on ASCS/MSCs by educating them to become cancer-associated fibroblasts. We conclude that ASCs/MSCs, especially obese ASCs/MSCs, may be key players in the breast cancer microenvironment. Targeting these cells may provide a new path of effective breast cancer treatment.

Stem cell-based therapy for human diseases

Recent advancements in stem cell technology open a new door for patients suffering from diseases and disorders that have yet to be treated. Stem cell-based therapy, including human pluripotent stem cells (hPSCs) and multipotent mesenchymal stem cells (MSCs), has recently emerged as a key player in regenerative medicine. hPSCs are defined as self-renewable cell types conferring the ability to differentiate into various cellular phenotypes of the human body, including three germ layers. MSCs are multipotent progenitor cells possessing self-renewal ability (limited in vitro) and differentiation potential into mesenchymal lineages, according to the International Society for Cell and Gene Therapy (ISCT). This review provides an update on recent clinical applications using either hPSCs or MSCs derived from bone marrow (BM), adipose tissue (AT), or the umbilical cord (UC) for the treatment of human diseases, including neurological disorders, pulmonary dysfunctions, metabolic/endocrine-related diseases, reproductive disorders, skin burns, and cardiovascular conditions. Moreover, we discuss our own clinical trial experiences on targeted therapies using MSCs in a clinical setting, and we propose and discuss the MSC tissue origin concept and how MSC origin may contribute to the role of MSCs in downstream applications, with the ultimate objective of facilitating translational research in regenerative medicine into clinical applications. The mechanisms discussed here support the proposed hypothesis that BM-MSCs are potentially good candidates for brain and spinal cord injury treatment, AT-MSCs are potentially good candidates for reproductive disorder treatment and skin regeneration, and UC-MSCs are potentially good candidates for pulmonary disease and acute respiratory distress syndrome treatment.

The Microenvironment That Regulates Vascular Wall Stem/Progenitor Cells in Vascular Injury and Repair

Vascular repair upon injury is a frequently encountered pathology in cardiovascular diseases, which is crucial for the maintenance of arterial homeostasis and function. Stem/progenitor cells located on vascular walls have multidirectional differentiation potential and regenerative ability. It has been demonstrated that stem/progenitor cells play an essential role in the basic medical research and disease treatment. The dynamic microenvironment around the vascular wall stem/progenitor cells (VW-S/PCs) possesses many stem cell niche-like characteristics to support and regulate cells' activities, maintaining the properties of stem cells. Under physiological conditions, vascular homeostasis is a cautiously balanced and efficient interaction between stem cells and the microenvironment. These interactions contribute to the vascular repair and remodeling upon vessel injury. However, the signaling mechanisms involved in the regulation of microenvironment on stem cells remain to be further elucidated. Understanding the functional characteristics and potential mechanisms of VW-S/PCs is of great significance for both basic and translational research. This review underscores the microenvironment-derived signals that regulate VW-S/PCs and aims at providing new targets for the treatment of related cardiovascular diseases.

Adipose-derived stromal cells increase the formation of collagens through paracrine and juxtacrine mechanisms in a fibroblast co-culture model utilizing macromolecular crowding

Background

Adipose-derived stromal cells (ASCs) possess a multitude of regenerative capabilities, which include immunomodulation, angiogenesis, and stimulation of extracellular matrix (ECM) remodeling. However, the underlying mechanisms leading to ECM remodeling remain largely elusive and highlight the need for functional in vitro models for mode of action studies. Therefore, the purpose of this study was to develop an in vitro co-culture model to investigate the capabilities of ASCs to modulate fibroblasts and ECM.

Methods

An ECM in vitro model with ASCs and normal human dermal fibroblasts (NHDFs) was established utilizing macromolecular crowding, ascorbic acid, and TGF-β stimulation. Paracrine and juxtacrine co-cultures were created using transwell inserts and cell cultures with direct cell–cell contacts. The cultures were screened using RT² PCR Profiler Arrays; the protein levels of myofibroblast differentiation marker alpha smooth muscle actin (αSMA) and ECM remodeling enzymes were analyzed using western blot on cell lysates; the formation of collagen type I, III, VI, and fibronectin was investigated using ELISA on culture supernatants; and the deposition of collagens was analyzed using immunocytochemistry.

Results

TGF-β stimulation of NHDF monocultures increased the expression of 18 transcripts relevant for ECM formation and remodeling, the protein levels of αSMA and matrix metalloproteinase-2 (MMP-2), the formation of collagen type I, III, VI, and fibronectin, and the deposition of collagen type I and VI and decreased the protein levels of MMP-14. Inclusion of ASCs in the ECM co-culture model increased the formation of collagen type I and III through paracrine mechanisms and the formation of collagen type VI through juxtacrine mechanisms.

Conclusions

The co-culture model provides effective stimulation of NHDF monocultures by TGF-β for enhanced formation and deposition of ECM. In the model, ASCs induce changes in ECM by increasing formation of collagen type I, III and VI. The obtained results could guide further investigations of ASCs’ capabilities and underlying mechanisms related to ECM formation and remodeling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02923-y.

Human Wharton's Jelly Mesenchymal Stem Cells Secretome Inhibits Human SARS-CoV-2 and Avian Infectious Bronchitis Coronaviruses

Human SARS-CoV-2 and avian infectious bronchitis virus (IBV) are highly contagious and deadly coronaviruses, causing devastating respiratory diseases in humans and chickens. The lack of effective therapeutics exacerbates the impact of outbreaks associated with SARS-CoV-2 and IBV infections. Thus, novel drugs or therapeutic agents are highly in demand for controlling viral transmission and disease progression. Mesenchymal stem cells (MSC) secreted factors (secretome) are safe and efficient alternatives to stem cells in MSC-based therapies. This study aimed to investigate the antiviral potentials of human Wharton’s jelly MSC secretome (hWJ-MSC-S) against SARS-CoV-2 and IBV infections in vitro and in ovo. The half-maximal inhibitory concentrations (IC50), cytotoxic concentration (CC50), and selective index (SI) values of hWJ-MSC-S were determined using Vero-E6 cells. The virucidal, anti-adsorption, and anti-replication antiviral mechanisms of hWJ-MSC-S were evaluated. The hWJ-MSC-S significantly inhibited infection of SARS-CoV-2 and IBV, without affecting the viability of cells and embryos. Interestingly, hWJ-MSC-S reduced viral infection by >90%, in vitro. The IC50 and SI of hWJ-MSC secretome against SARS-CoV-2 were 166.6 and 235.29 µg/mL, respectively, while for IBV, IC50 and SI were 439.9 and 89.11 µg/mL, respectively. The virucidal and anti-replication antiviral effects of hWJ-MSC-S were very prominent compared to the anti-adsorption effect. In the in ovo model, hWJ-MSC-S reduced IBV titer by >99%. Liquid chromatography-tandem mass spectrometry (LC/MS-MS) analysis of hWJ-MSC-S revealed a significant enrichment of immunomodulatory and antiviral proteins. Collectively, our results not only uncovered the antiviral potency of hWJ-MSC-S against SARS-CoV-2 and IBV, but also described the mechanism by which hWJ-MSC-S inhibits viral infection. These findings indicate that hWJ-MSC-S could be utilized in future pre-clinical and clinical studies to develop effective therapeutic approaches against human COVID-19 and avian IB respiratory diseases.

Strategy for Conjugating Oligopeptides to Mesoporous Silica Nanoparticles Using Diazirine-Based Heterobifunctional Linkers

Successful strategies for the attachment of oligopeptides to mesoporous silica with pores large enough to load biomolecules should utilize the high surface area of pores to provide an accessible, protective environment. A two-step oligopeptide functionalization strategy is examined here using diazirine-based heterobifunctional linkers. Mesoporous silica nanoparticles (MSNPs) with average pore diameter of ~8 nm and surface area of ~730 m²/g were synthesized and amine-functionalized. Tetrapeptides Gly-Gly-Gly-Gly (GGGG) and Arg-Ser-Ser-Val (RSSV), and a peptide comprised of four copies of RSSV (4RSSV), were covalently attached via their N-terminus to the amine groups on the particle surface by a heterobifunctional linker, sulfo-succinimidyl 6-(4,4′-azipentanamido)hexanoate (sulfo-NHS-LC-diazirine, or SNLD). SNLD consists of an amine-reactive NHS ester group and UV-activable diazirine group, providing precise control over the sequence of attachment steps. Attachment efficiency of RSSV was measured using fluorescein isothiocyanate (FITC)-tagged RSSV (RSSV-FITC). TGA analysis shows similar efficiency (0.29, 0.31 and 0.26 mol peptide/mol amine, respectively) for 4G, RSSV and 4RSSV, suggesting a generalizable method of peptide conjugation. The technique developed here for the conjugation of peptides to MSNPs provides for their attachment in pores and can be translated to selective peptide-based separation and concentration of therapeutics from aqueous process and waste streams.

Extracellular Matrix Synthesis and Remodeling by Mesenchymal Stromal Cells Is Context-Sensitive

Matrix remodeling could be an important mode of action of multipotent mesenchymal stromal cells (MSC) in extracellular matrix (ECM) disease, but knowledge is limited in this respect. As MSC are well-known to adapt their behavior to their environment, we aimed to investigate if their mode of action would change in response to healthy versus pathologically altered ECM. Human MSC-derived ECM was produced under different culture conditions, including standard culture, culture on Matrigel-coated dishes, and stimulation with the pro-fibrotic transforming growth factor-β1 (TGFβ1). The MSC-ECM was decellularized, characterized by histochemistry, and used as MSC culture substrate reflecting different ECM conditions. MSC were cultured on the different ECM substrates or in control conditions for 2 days. Culture on ECM increased the presence of surface molecules with ECM receptor function in the MSC, demonstrating an interaction between MSC and ECM. In MSC cultured on Matrigel-ECM and TGFβ1-ECM, which displayed a fibrosis-like morphology, gene expression of collagens and decorin, as well as total matrix metalloproteinase (MMP) activity in the supernatant were decreased as compared with control conditions. These results demonstrated that MSC adapt to their ECM environment, which may include pathological adaptations that could compromise therapeutic efficacy.

State of the Art: The Immunomodulatory Role of MSCs for Osteoarthritis

Osteoarthritis (OA) has generally been introduced as a degenerative disease; however, it has recently been understood as a low-grade chronic inflammatory process that could promote symptoms and accelerate the progression of OA. Current treatment strategies, including corticosteroid injections, have no impact on the OA disease progression. Mesenchymal stem cells (MSCs) based therapy seem to be in the spotlight as a disease-modifying treatment because this strategy provides enlarged anti-inflammatory and chondroprotective effects. Currently, bone marrow, adipose derived, synovium-derived, and Wharton's jelly-derived MSCs are the most widely used types of MSCs in the cartilage engineering. MSCs exert immunomodulatory, immunosuppressive, antiapoptotic, and chondrogenic effects mainly by paracrine effect. Because MSCs disappear from the tissue quickly after administration, recently, MSCs-derived exosomes received the focus for the next-generation treatment strategy for OA. MSCs-derived exosomes contain a variety of miRNAs. Exosomal miRNAs have a critical role in cartilage regeneration by immunomodulatory function such as promoting chondrocyte proliferation, matrix secretion, and subsiding inflammation. In the future, a personalized exosome can be packaged with ideal miRNA and proteins for chondrogenesis by enriching techniques. In addition, the target specific exosomes could be a gamechanger for OA. However, we should consider the off-target side effects due to multiple gene targets of miRNA.

Adipose Stem Cell-Based Treatments for Wound Healing

Wound healing is one of the most complex physiological regulation mechanisms of the human body. Stem cell technology has had a significant impact on regenerative medicine. Adipose stem cells (ASCs) have many advantages, including their ease of harvesting and high yield, rich content of cell components and cytokines, and strong practicability. They have rapidly become a favored tool in regenerative medicine. Here, we summarize the mechanism and clinical therapeutic potential of ASCs in wound repair.

Stem Cell Mimicking Nanoencapsulation for Targeting Arthritis

Mesenchymal stem cells (MSCs) are considered a promising regenerative therapy due to their ability to migrate toward damaged tissues. The homing ability of MSCs is unique compared with that of non-migrating cells and MSCs are considered promising therapeutic vectors for targeting major cells in many pathophysiological sites. MSCs have many advantages in the treatment of malignant diseases, particularly rheumatoid arthritis (RA). RA is a representative autoimmune disease that primarily affects joints, and secreted chemokines in the joints are well recognized by MSCs following their migration to the joints. Furthermore, MSCs can regulate the inflammatory process and repair damaged cells in the joints. However, the functionality and migration ability of MSCs injected in vivo still show insufficient. The targeting ability and migration efficiency of MSCs can be enhanced by genetic engineering or modification, eg, overexpressing chemokine receptors or migration-related genes, thus maximizing their therapeutic effect. However, there are concerns about genetic changes due to the increased probability of oncogenesis resulting from genome integration of the viral vector, and thus, clinical application is limited. Furthermore, it is suspected that administering MSCs can promote tumor growth and metastasis in xenograft and orthotopic models. For this reason, MSC mimicking nanoencapsulations are an alternative strategy that does not involve using MSCs or bioengineered MSCs. MSC mimicking nanoencapsulations consist of MSC membrane-coated nanoparticles, MSC-derived exosomes and artificial ectosomes, and MSC membrane-fused liposomes with natural or genetically engineered MSC membranes. MSC mimicking nanoencapsulations not only retain the targeting ability of MSCs but also have many advantages in terms of targeted drug delivery. Specifically, MSC mimicking nanoencapsulations are capable of encapsulating drugs with various components, including chemotherapeutic agents, nucleic acids, and proteins. Furthermore, there are fewer concerns over safety issues on MSC mimicking nanoencapsulations associated with mutagenesis even when using genetically engineered MSCs, because MSC mimicking nanoencapsulations use only the membrane fraction of MSCs. Genetic engineering is a promising route in clinical settings, where nano-encapsulated technology strategies are combined. In this review, the mechanism underlying MSC homing and the advantages of MSC mimicking nanoencapsulations are discussed. In addition, genetic engineering of MSCs and MSC mimicking nanoencapsulation is described as a promising strategy for the treatment of immune-related diseases.

Inhibition of aberrant tissue remodelling by mesenchymal stromal cells singly coated with soft gels presenting defined chemomechanical cues

The precise understanding and control of microenvironmental cues could be used to optimize the efficacy of cell therapeutics. Here, we show that mesenchymal stromal cells (MSCs) singly coated with a soft conformal gel presenting defined chemomechanical cues promote matrix remodelling by secreting soluble interstitial collagenases in response to the presence of tumour necrosis factor alpha (TNF-α). In mice with fibrotic lung injury, treatment with the coated MSCs maintained normal collagen levels, fibre density and microelasticity in lung tissue, and the continuous presentation of recombinant TNF-α in the gel facilitated the reversal of aberrant tissue remodelling by the cells when inflammation subsided in the host. Gel coatings with predefined chemomechanical cues could be used to tailor cells with specific mechanisms of action for desired therapeutic outcomes.

Mechanism of Action of Mesenchymal Stem Cells (MSCs): impact of delivery method

INTRODUCTION

Mesenchymal stromal cells (MSCs; AKA mesenchymal stem cells) stimulate healing and reduce inflammation. Promising therapeutic responses are seen in many late-phase clinical trials, but others have not satisfied their primary endpoints, making translation of MSCs into clinical practice difficult. These inconsistencies may be related to the route of MSC delivery, lack of product optimization, or varying background therapies received in clinical trials over time.

AREAS COVERED

Here we discuss the different routes of MSC delivery, highlighting the proposed mechanism(s) of therapeutic action as well as potential safety concerns. PubMed search criteria used: MSC plus: local administration; routes of administration; delivery methods; mechanism of action; therapy in different diseases.

EXPERT OPINION

Direct injection of MSCs using a controlled local delivery approach appears to have benefits in certain disease states, but further studies are required to make definitive conclusions regarding the superiority of one delivery method over another.

Human adipose tissue-derived mesenchymal stromal cells and their phagocytic capacity

Mesenchymal stromal cells (MSCs) have evidenced considerable therapeutic potential in numerous clinical fields, especially in tissue regeneration. The immunological characteristics of this cell population include the expression of Toll‐like receptors and mannose receptors, among others. The study objective was to determine whether MSCs have phagocytic capacity against different target particles. We isolated and characterized three human adipose tissue MSC (HAT‐MSC) lines from three patients and analysed their phagocytic capacity by flow cytometry, using fluorescent latex beads, and by transmission electron microscopy, using Escherichia coli, Staphylococcus aureus and Candida albicans as biological materials and latex beads as non‐biological material. The results demonstrate that HAT‐MSCs can phagocyte particles of different nature and size. The percentage of phagocytic cells ranged between 33.8% and 56.2% (mean of 44.37% ± 11.253) according to the cell line, and a high phagocytic index was observed. The high phagocytic capacity observed in MSCs, which have known regenerative potential, may offer an advance in the approach to certain local and systemic infections.

Mesenchymal Stromal Cells Adapt to Chronic Tendon Disease Environment with an Initial Reduction in Matrix Remodeling

Tendon lesions are common sporting injuries in humans and horses alike. The healing process of acute tendon lesions frequently results in fibrosis and chronic disease. In horses, local mesenchymal stromal cell (MSC) injection is an accepted therapeutic strategy with positive influence on acute lesions. Concerning the use of MSCs in chronic tendon disease, data are scarce but suggest less therapeutic benefit. However, it has been shown that MSCs can have a positive effect on fibrotic tissue. Therefore, we aimed to elucidate the interplay of MSCs and healthy or chronically diseased tendon matrix. Equine MSCs were cultured either as cell aggregates or on scaffolds from healthy or diseased equine tendons. Higher expression of tendon-related matrix genes and tissue inhibitors of metalloproteinases (TIMPs) was found in aggregate cultures. However, the tenogenic transcription factor scleraxis was upregulated on healthy and diseased tendon scaffolds. Matrix metalloproteinase (MMPs) expression and activity were highest in healthy scaffold cultures but showed a strong transient decrease in diseased scaffold cultures. The release of glycosaminoglycan and collagen was also higher in scaffold cultures, even more so in those with tendon disease. This study points to an early suppression of MSC matrix remodeling activity by diseased tendon matrix, while tenogenic differentiation remained unaffected.

Bone Regeneration Using MMP-Cleavable Peptides-Based Hydrogels

Accumulating evidence has suggested the significant potential of chemically modified hydrogels in bone regeneration. Despite the progress of bioactive hydrogels with different materials, structures and loading cargoes, the desires from clinical applications have not been fully validated. Multiple biological behaviors are orchestrated precisely during the bone regeneration process, including bone marrow mesenchymal stem cells (BMSCs) recruitment, osteogenic differentiation, matrix calcification and well-organized remodeling. Since matrix metalloproteinases play critical roles in such bone metabolism processes as BMSC commitment, osteoblast survival, osteoclast activation matrix calcification and microstructure remodeling, matrix metalloproteinase (MMP) cleavable peptides-based hydrogels could respond to various MMP levels and, thus, accelerate bone regeneration. In this review, we focused on the MMP-cleavable peptides, polymers, functional modification and crosslinked reactions. Applications, perspectives and limitations of MMP-cleavable peptides-based hydrogels for bone regeneration were then discussed.

Towards a bioengineered uterus: bioactive sheep uterus scaffolds are effectively recellularized by enzymatic preconditioning

Uterine factor infertility was considered incurable until recently when we reported the first successful live birth after uterus transplantation. However, risky donor surgery and immunosuppressive therapy are factors that may be avoided with bioengineering. For example, transplanted recellularized constructs derived from decellularized tissue restored fertility in rodent models and mandate translational studies. In this study, we decellularized whole sheep uterus with three different protocols using 0.5% sodium dodecyl sulfate, 2% sodium deoxycholate (SDC) or 2% SDC, and 1% Triton X-100. Scaffolds were then assessed for bioactivity using the dorsal root ganglion and chorioallantoic membrane assays, and we found that all the uterus scaffolds exhibited growth factor activity that promoted neurogenesis and angiogenesis. Extensive recellularization optimization was conducted using multipotent sheep fetal stem cells and we report results from the following three in vitro conditions; (a) standard cell culturing conditions, (b) constructs cultured in transwells, and (c) scaffolds preconditioned with matrix metalloproteinase 2 and 9. The recellularization efficiency was improved short-term when transwells were used compared with standard culturing conditions. However, the recellularization efficiency in scaffolds preconditioned with matrix metalloproteinases was 200–300% better than the other strategies evaluated herein, independent of decellularization protocol. Hence, a major recellularization hurdle has been overcome with the improved recellularization strategies and in vitro platforms described herein. These results are an important milestone and should facilitate the production of large bioengineered grafts suitable for future in vivo applications in the sheep, which is an essential step before considering these principles in a clinical setting.

Skin Immunomodulation during Regeneration: Emerging New Targets

Adipose-Derived Stem Cells (ADSC) are present within the hypodermis and are also expected to play a pivotal role in wound healing, immunomodulation, and rejuvenation activities. They orchestrate, through their exosome, the mechanisms associated to cell differentiation, proliferation, and cell migration by upregulating genes implicated in different functions including skin barrier, immunomodulation, cell proliferation, and epidermal regeneration. ADSCs directly interact with their microenvironment and specifically the immune cells, including macrophages and T and B cells, resulting in differential inflammatory and anti-inflammatory mechanisms impacting, in return, ADSCs microenvironment and thus skin function. These useful features of ADSCs are involved in tissue repair, where the required cell proliferation, angiogenesis, and anti-inflammatory responses should occur rapidly in damaged sites. Different pathways involved have been reported such as Growth Differentiation Factor-11 (GDF11), Tumor Growth Factor (TGF)-β, Metalloproteinase (MMP), microRNA, and inflammatory cytokines that might serve as specific biomarkers of their immunomodulating capacity. In this review, we try to highlight ADSCs’ network and explore the potential indicators of their immunomodulatory effect in skin regeneration and aging. Assessment of these biomarkers might be useful and should be considered when designing new clinical therapies using ADSCs or their specific exosomes focusing on their immunomodulation activity.

Deciphering the Relevance of Bone ECM Signaling

Bone mineral density, a bone matrix parameter frequently used to predict fracture risk, is not the only one to affect bone fragility. Other factors, including the extracellular matrix (ECM) composition and microarchitecture, are of paramount relevance in this process. The bone ECM is a noncellular three-dimensional structure secreted by cells into the extracellular space, which comprises inorganic and organic compounds. The main inorganic components of the ECM are calcium-deficient apatite and trace elements, while the organic ECM consists of collagen type I and noncollagenous proteins. Bone ECM dynamically interacts with osteoblasts and osteoclasts to regulate the formation of new bone during regeneration. Thus, the composition and structure of inorganic and organic bone matrix may directly affect bone quality. Moreover, proteins that compose ECM, beyond their structural role have other crucial biological functions, thanks to their ability to bind multiple interacting partners like other ECM proteins, growth factors, signal receptors and adhesion molecules. Thus, ECM proteins provide a complex network of biochemical and physiological signals. Herein, we summarize different ECM factors that are essential to bone strength besides, discussing how these parameters are altered in pathological conditions related with bone fragility.

Designing Enzyme-responsive Biomaterials

Enzymes are a class of protein that catalyze a wide range of chemical reactions, including the cleavage of specific peptide bonds. They are expressed in all cell types, play vital roles in tissue development and homeostasis, and in many diseases, such as cancer. Enzymatic activity is tightly controlled through the use of inactive pro-enzymes, endogenous inhibitors and spatial localization. Since the presence of specific enzymes is often correlated with biological processes, and these proteins can directly modify biomolecules, they are an ideal biological input for cell-responsive biomaterials. These materials include both natural and synthetic polymers, cross-linked hydrogels and self-assembled peptide nanostructures. Within these systems enzymatic activity has been used to induce biodegradation, release therapeutic agents and for disease diagnosis. As technological advancements increase our ability to quantify the expression and nanoscale organization of proteins in cells and tissues, as well as the synthesis of increasingly complex and well-defined biomaterials, enzyme-responsive biomaterials are poised to play vital roles in the future of biomedicine.

Randomized controlled study for the anti-aging effect of human adipocyte-derived mesenchymal stem cell media combined with niacinamide after laser therapy

BACKGROUND

Recent advancements in laser-assisted drug delivery have emphasized the importance of post-laser use of active ingredients.

AIMS

We evaluated the effect of topical post-laser treatment with adipocyte-derived stem cell-containing medium (ADSC-CM) in combination with niacinamide through a double-blind, randomized, vehicle-controlled study.

PATIENTS/METHODS

Twenty-five patients with aging skin underwent ablative fractional laser (AFL) treatment on both sides of the face for skin rejuvenation. Moisturizers with or without ADSC-CM plus 2% niacinamide was applied to the designated sides of faces for 3 weeks. The wrinkle and the melanin indices were assessed using a specialized digital photography analyzer. Additional in vitro assays were performed.

RESULTS

The wrinkle index, melanin index, patient satisfaction score, and the investigator's global esthetic improvement scale (GAIS) after use of ADSC-CM plus niacinamide were significantly higher than after use of the vehicle cream. The in vitro UVB irradiation assays with human keratinocytes showed decreased levels of pro-inflammatory cytokines upon incubation with ADSC-CM plus niacinamide, and the cell scratch assay displayed decreased MMP-1 and MMP-2 expression as well as increased Type 1 collagen expression.

CONCLUSIONS

We demonstrated that post-laser topical application of ADSC-CM in combination with niacinamide has anti-aging effect on skin.

Research progress on Mesenchymal Stem Cells (MSCs), Adipose-Derived Mesenchymal Stem Cells (AD-MSCs), Drugs, and Vaccines in Inhibiting COVID-19 Disease

Mesenchymal Stem Cells (MSCs), and Adipose-Derived Mesenchymal Stem Cells (AD-MSCs) have been used for many years in regenerative medicine for clinical and surgical applications. Additionally, recent studies reported improved respiratory activity after intravenous administration of MSCs into patients affected by coronavirus disease 2019 (COVID-19) caused by the Coronavirus 2 (SARS-CoV-2) suggesting their role as anti-viral therapy. Severe COVID-19 patients usually progress to acute respiratory distress syndrome, sepsis, metabolic acidosis that is difficult to correct, coagulation dysfunction, multiple organ failure, and even death in a short period after onset. Currently, there is still a lack of clinically effective drugs for such patients. The high secretory activity, the immune-modulatory effect, and the homing ability make MSCs and in particular AD-MSCs both a potential tool for the anti-viral drug-delivery in the virus microenvironment and potential cellular therapy. AD-MSCs as the most important exponent of MSCs are expected to reduce the risk of complications and death of patients due to their strong anti-inflammatory and immune-modulatory capabilities, which can improve microenvironment, promote neovascularization and enhance tissue repair capabilities. In this literature review, the role of regenerative strategies through MSCs, AD-MSCs, and adipocyte-secreted exosomal microRNAs (A-SE-miRs) as a potential antiviral therapy was reported, comparing the results found with current research progress on drugs and vaccines in COVID-19 disease.

Endogenous cell recruitment strategy for articular cartilage regeneration

In the absence of timely and proper treatments, injuries to articular cartilage (AC) can lead to cartilage degeneration and ultimately result in osteoarthritis. Regenerative medicine and tissue engineering techniques are emerging as promising approaches for AC regeneration and repair. Although the use of cell-seeded scaffolds prior to implantation can regenerate and repair cartilage lesions to some extent, these approaches are still restricted by limited cell sources, excessive costs, risks of disease transmission and complex manufacturing practices. Recently developed acellular scaffold approaches that rely on the recruitment of endogenous cells to the injured sites avoid these drawbacks and offer great promise for in situ AC regeneration. Multiple endogenous stem/progenitor cells (ESPCs) are found in joint-resident niches and have the capability to migrate to sites of injury to participate in AC regeneration. However, the natural recruitment of ESPCs is insufficient, and the local microenvironment is hostile after injury. Hence, an endogenous cell recruitment strategy based on the combination of chemoattractants and acellular scaffolds to effectively and specifically recruit ESPCs and improve local microenvironment may provide new insights into in situ AC regeneration. This review provides a brief overview of: (1) the status of endogenous cell recruitment strategy; (2) the subpopulations, potential migration routes (PMRs) of joint-resident ESPCs and their immunomodulatory and reparative effects; (3) chemoattractants and their potential adverse effects; (4) scaffold-based drug delivery systems (SDDSs) that are utilized for in situ AC regeneration; and (5) the challenges and future perspectives of endogenous cell recruitment strategy for AC regeneration. STATEMENT OF SIGNIFICANCE: Although the endogenous cell recruitment strategy for articular cartilage (AC) regeneration has been investigated for several decades, much work remains to be performed in this field. Future studies should have the following aims: (1) reporting the up-to-date progress in the endogenous cell recruitment strategies; (2) determining the subpopulations of ESPCs, the cellular and molecular mechanisms underlying the migration of these cells and their anti-inflammatory, immunomodulatory and reparative effects; (3) elucidating the chemoattractants that enhance ESPC recruitment and their potential adverse effects; and (4) developing advanced SDDSs for chemoattractant dispatch. Herein, we present a systematic overview of the aforementioned issues to provide a better understanding of endogenous cell recruitment strategies for AC regeneration and repair.

Determining How Human Mesenchymal Stem Cells Change Their Degradation Strategy in Response to Microenvironmental Stiffness

During the wound healing process, human mesenchymal stem cells (hMSCs) are recruited to the injury where they regulate inflammation and initiate healing and tissue regeneration. To aid in healing, synthetic cell-laden hydrogel scaffolds are being designed to deliver additional hMSCs to wounds to enhance or restart the healing process. These scaffolds are being designed to mimic native tissue environments, which include physical cues, such as scaffold stiffness. In this work, we focus on how the initial scaffold stiffness hMSCs are encapsulated in changes cell-mediated remodeling and degradation and motility. To do this, we encapsulate hMSCs in a well-defined synthetic hydrogel scaffold that recapitulates aspects of the native extracellular matrix (ECM). We then characterize cell-mediated degradation in the pericellular region as a function of initial microenvironmental stiffness. Our hydrogel consists of a 4-arm poly(ethylene glycol) (PEG) end-functionalized with norbornene which is chemically cross-linked with a matrix metalloproteinase (MMP) degradable peptide sequence. This peptide sequence is cleaved by hMSC-secreted MMPs. The hydrogel elastic modulus is varied from 80 to 2400 Pa by changing the concentration of the peptide cross-linker. We use multiple particle tracking microrheology (MPT) to characterize the spatiotemporal cell-mediated degradation in the pericellular region. In MPT, fluorescently labeled particles are embedded in the material, and their Brownian motion is measured. We measure an increase in cell-mediated degradation and remodeling as the post-encapsulation time increases. MPT also measures changes in the degradation profile in the pericellular region as hydrogel stiffness is increased. We hypothesize that the change in the degradation profile is due to a change in the amount and type of molecules secreted by hMSCs. We also measure a significant decrease in cell speed as hydrogel stiffness increases due to the increased physical barrier that needs to be degraded to enable motility. These measurements increase our understanding of the rheological changes in the pericellular region in different physical microenvironments which could lead to better design of implantable biomaterials for cell delivery to wounded areas.

Destroy to Rebuild: The Connection Between Bone Tissue Remodeling and Matrix Metalloproteinases

Bone is a dynamic organ that undergoes constant remodeling, an energetically costly process by which old bone is replaced and localized bone defects are repaired to renew the skeleton over time, thereby maintaining skeletal health. This review provides a general overview of bone’s main players (bone lining cells, osteocytes, osteoclasts, reversal cells, and osteoblasts) that participate in bone remodeling. Placing emphasis on the family of extracellular matrix metalloproteinases (MMPs), we describe how: (i) Convergence of multiple protease families (including MMPs and cysteine proteinases) ensures complexity and robustness of the bone remodeling process, (ii) Enzymatic activity of MMPs affects bone physiology at the molecular and cellular levels and (iii) Either overexpression or deficiency/insufficiency of individual MMPs impairs healthy bone remodeling and systemic metabolism. Today, it is generally accepted that proteolytic activity is required for the degradation of bone tissue in osteoarthritis and osteoporosis. However, it is increasingly evident that inactivating mutations in MMP genes can also lead to bone pathology including osteolysis and metabolic abnormalities such as delayed growth. We argue that there remains a need to rethink the role played by proteases in bone physiology and pathology.

Mesenchymal VEGFA induces aberrant differentiation in heterotopic ossification

Heterotopic ossification (HO) is a debilitating condition characterized by the pathologic formation of ectopic bone. HO occurs commonly following orthopedic surgeries, burns, and neurologic injuries. While surgical excision may provide palliation, the procedure is often burdened with significant intra-operative blood loss due to a more robust contribution of blood supply to the pathologic bone than to native bone. Based on these clinical observations, we set out to examine the role of vascular signaling in HO. Vascular endothelial growth factor A (VEGFA) has previously been shown to be a crucial pro-angiogenic and pro-osteogenic cue during normal bone development and homeostasis. Our findings, using a validated mouse model of HO, demonstrate that HO lesions are highly vascular, and that VEGFA is critical to ectopic bone formation, despite lacking a contribution of endothelial cells within the developing anlagen.

Hyaluronic acid as a macromolecular crowding agent for production of cell-derived matrices

Cell-derived matrices (CDMs) provide an exogenous source of human extracellular matrix (ECM), with applications as cell delivery vehicles, substrate coatings for cell attachment and differentiation, and as biomaterial scaffolds. However, commercial application of CDMs has been hindered due to the prolonged culture time required for sufficient ECM accumulation. One approach to increasing matrix deposition in vitro is macromolecular crowding (MMC), which is a biophysical phenomenon that limits the diffusion of ECM precursor proteins, resulting in increased ECM accumulation at the cell layer. Hyaluronic acid (HA), a natural MMC highly expressed in vivo during fetal development, has been shown to play a role in ECM production, but has not been investigated as a macromolecule for increasing cell-mediated ECM deposition in vitro. In the current study, we hypothesized that HA can act as a MMC, and increase cell-mediated ECM production. Human dermal fibroblasts were cultured for 3, 7, or 14 days with 0%, 0.05%, or 0.5% high molecular weight HA. Ficoll 70/400 was used as a positive control. SDS-PAGE, Sircol, and hydroxyproline assays indicated that 0.05% HA-treated cultures had significantly higher mean collagen deposition at 14 days, whereas Ficoll 70/400-treated cultures had significantly lower collagen production compared to the HA and untreated controls. However, fluorescent immunostaining of ECM proteins and quantification of mean gray values did not indicate statistically significant differences in ECM production in HA or Ficoll 70/400-treated cultures compared to untreated controls. Raman imaging (a marker-free spectral imaging method) indicated that HA increased ECM deposition in human dermal fibroblasts. These results are consistent with decreases in CDM stiffness observed in Ficoll 70/400-treated cultures by atomic force microscopy. Overall, these results indicate that there are macromolecule- and cell type- dependent effects on matrix assembly, turnover, and stiffness in cell-derived matrices. STATEMENT OF SIGNIFICANCE: Cell-derived matrices (CDMs) are versatile biomaterials with many regenerative medicine applications, including as cell and drug delivery vehicles and scaffolds for wound healing and tissue regeneration. While CDMs have several advantages, their commercialization has been limited due to the prolonged culture time required to achieve CDM synthesis in vitro. In this study, we explored the use of hyaluronic acid (HA) as a macromolecular crowder in human fibroblast cell cultures to support production of CDM biomaterials. Successful application of macromolecular crowding will allow development of human cell-derived, xeno-free biomaterials that re-capitulate the native human tissue microenvironment.

Characterizing the dynamic rheology in the pericellular region by human mesenchymal stem cell re-engineering in PEG-peptide hydrogel scaffolds

During wound healing, human mesenchymal stem cells (hMSCs) migrate to injuries to regulate inflammation and coordinate tissue regeneration. To enable migration, hMSCs re-engineer the extracellular matrix rheology. Our work determines the correlation between cell engineered rheology and motility. We encapsulate hMSCs in a cell-degradable peptide-polymeric hydrogel and characterize the change in rheological properties in the pericellular region using multiple particle tracking microrheology. Previous studies determined that pericellular rheology is correlated with motility. Additionally, hMSCs re-engineer their microenvironment by regulating cell-secreted enzyme, matrix metallopro-teinases (MMPs), activity by also secreting their inhibitors, tissue inhibitors of metalloproteinases (TIMPs). We independently inhibit TIMPs and measure two different degradation profiles, reaction-diffusion and reverse reaction-diffusion. These profiles are correlated with cell spreading, speed and motility type. We model scaffold degradation using Michaelis-Menten kinetics, finding a decrease in kinetics between joint and independent TIMP inhibition. hMSCs ability to regulate microenvironmental remodeling and motility could be exploited in design of new materials that deliver hMSCs to wounds to enhance healing.

Mesenchymal Stem Cell Transplantation Promotes Functional Recovery through MMP2/STAT3 Related Astrogliosis after Spinal Cord Injury

Background and Objectives

Treatment with mesenchymal stem cells (MSC) in spinal cord injury (SCI) has been highlighted as therapeutic candidate for SCI. Although astrogliosis is a major phenomenon after SCI, the role of astrogliosis is still controversial. In this study, we determined whether acute transplantation of MSC improves the outcome of SCI through modulating astrogliosis.

Methods

Bone marrow derived rat MSCs were induced neural differentiation and transplanted after acute SCI rats. Matrix metalloproteinase (MMP) and neuro-inflammatory pathway were analyzed for acute astrogliosis at 1, 3 and 7 d after SCI in RT-PCR- and western blot analysis. Functional outcome was assessed serially at postoperative 1 d and weekly for 4 weeks. Histopathologic analysis was undertaken at 7 and 28 d following injury in immunohistochemistry.

Results

Transplantation of MSCs decreased IL-1α, CXCL-2, CXCL-10, TNF-α and TGF-β in a rat model of contusive SCI. Protein level of NF-κB p65 was slightly decreased while level of STAT-3 was increased. In immunohistochemistry, MSC transplantation increased acute astrogliosis whereas attenuated scar formation with increased sparing white matter of spinal cord lesions. In RT-PCR analysis, mRNA levels of MMP2 was significantly increased in MSC transplanted rats. In BBB locomotor scale, the rats of MSC treated group exhibited improvement of functional recovery.

Conclusions

Transplantation of MSC reduces the inflammatory reaction and modulates astrogliosis via MMP2/STAT3 pathway leading to improve functional recovery after SCI in rats.

The effect of human umbilical cord blood-derived mesenchymal stem cell media containing serum on recovery after laser treatment: A double-blinded, randomized, split-face controlled study

BACKGROUND

Ablative CO2 fractional laser (AFL) is a common cosmetic procedure to improve skin laxity. However, due to prolonged downtime and the risk of postinflammatory hyperpigmentation, laser-assisted delivery of active ingredients as post-laser treatment has gained interest in past years. Among various active ingredients, human umbilical cord blood-derived mesenchymal stem cells (hUCBMSCs) can be a promising agent promoting skin regeneration.

AIMS

We evaluated the efficacy and safety of a human cord blood cell-conditioned media containing serum and cream on patients who underwent AFL treatment. A randomized, investigator-blinded, prospective, split-face comparison study was conducted.

MATERIALS AND METHODS

Twenty-three patients who underwent AFL on both cheeks applied a human umbilical cord blood-derived mesenchymal stem cell (hUCBMSC)-conditioned media containing cream with or without stem cell containing serum application. As a primary outcome measure, we evaluated the total area of microcrusts and post-treatment erythema using digital photographs. Additionally, skin biophysical parameters (corneometer, TEWL) and global improvement scores for skin texture were assessed.

RESULTS

The area of total microcrusts was reduced in the study group which applied both serum and cream. The global improvement score of the post-treatment erythema was significantly reduced. Investigator-assessed global improvement scores were higher in the combination treatment group. Additionally, there was no adverse event, which was associated with the use of either hUCBMSCs containing serum or cream.

CONCLUSION

The application of human cord blood cell containing serum and cream resulted in accelerated wound healing and reduced post-treatment erythema, which effectively reduced recovery time after ablative laser treatment.