Challenges and Strategies for Improving the Regenerative Effects of Mesenchymal Stromal Cell-Based Therapies

The Effect of Photobiomodulation on Human Mesenchymal Cells: A Literature Review

BACKGROUND

Mesenchymal stem cell-based therapy is known to have the potential to induce angiogenesis. However, there are still some limitations regarding their clinical application. Photomodulation/photobiomodulation is non-invasive and non-toxic phototherapy able to stimulate cell viability, proliferation, differentiation, and migration, when the right irradiation parameters are applied. A review of the published articles on human conditioned-by-photobiomodulation mesenchymal cells in an in vitro set up was carried out. Our aim was to describe the studies' results and identify any possible tendency that might highlight the most suitable procedures.

METHODS

A search in English of the PubMed database was carried out with the search criteria: photobiomodulation or photoactivation or photomodulation, and mesenchymal cells. All irradiations applied in vitro, on human mesenchymal cells, with wavelengths ranged from 600 to 1000 nm.

RESULTS

The search yielded 42 original articles and five reviews. Finally, 37 articles were selected with a total of 43 procedures. Three procedures (7.0%) from 620 to 625 nm; 26 procedures (60.5%) from 625 to 740 nm; 13 procedures (30.2%) from 740 to 1000 nm; and one procedure (2.3%) with combinations of wavelengths. Of the 43 procedures, 14 assessed cell viability (n = 14/43, 32.6%); 34 cell proliferation (n = 34/43, 79.1%); 19 cell differentiation (n = 19/43, 44.2%); and three cell migration (n = 3/43, 7.0%).

CONCLUSIONS

Photobiomodulation is a promising technology that can impact on cell viability, differentiation, proliferation, or migration, leading to enhance its regenerative capacity.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Biomaterials-assisted spheroid engineering for regenerative therapy

Cell-based therapy is a promising approach in the field of regenerative medicine. As cells are formed into spheroids, their survival, functions, and engraftment in the transplanted site are significantly improved compared to single cell transplantation. To improve the therapeutic effect of cell spheroids even further, various biomaterials (e.g., nano- or microparticles, fibers, and hydrogels) have been developed for spheroid engineering. These biomaterials not only can control the overall spheroid formation (e.g., size, shape, aggregation speed, and degree of compaction), but also can regulate cell-to-cell and cell-to-matrix interactions in spheroids. Therefore, cell spheroids in synergy with biomaterials have recently emerged for cell-based regenerative therapy. Biomaterials-assisted spheroid engineering has been extensively studied for regeneration of bone or/and cartilage defects, critical limb ischemia, and myocardial infarction. Furthermore, it has been expanded to pancreas islets and hair follicle transplantation. This paper comprehensively reviews biomaterials-assisted spheroid engineering for regenerative therapy.

Hyaluronic Acid Hydrogel Microspheres for Slow Release Stem Cell Delivery

Cell therapies are hampered by a lack of available delivery systems, resulting in inconsistent outcomes in animal studies and human clinical trials. Hydrogel encapsulants offer a broad range of tunable characteristics in the design of cell delivery vehicles. The focus of the hydrogel field has been on durable encapsulants that provide long-term paracrine function of the cells. However, some cell therapies require cell-to-cell contact in order to elicit their effect. Controlled release microencapsulants would be beneficial in these situations, but appropriate polymers have not been adaptable to microsphere manufacturing because they harden too slowly. We developed and tested a novel microencapsulant formulation (acrylated hyaluronic acid: AHA) with degradation characteristics as a controlled release cell delivery vehicle. The properties of AHA microspheres were evaluated and compared to those of poly(ethylene glycol) diacrylate (PEGDA), a durable hydrogel. AHA microspheres possessed a higher swelling ratio, lower diffusion barrier, faster degradation rate, a lower storage modulus, and a larger average diameter than microspheres composed of PEGDA. Additionally, in vitro cell viability and release and short-term in vivo biocompatibility in immune competent Sprague-Dawley rats was assessed for each microsphere type. Compared to PEGDA, microspheres composed of AHA resulted in significantly less foreign body response in vivo as measured by a lack of cellularity or fibrotic ring in the surrounding tissue and no cellular infiltration into the microsphere. This study illustrates the potential of AHA microspheres as a degradable cell delivery system with superior encapsulated cell viability and biocompatibility with the surrounding tissue.

Neurological Manifestation of SARS-CoV-2 Induced Inflammation and Possible Therapeutic Strategies Against COVID-19

There are regular reports of extrapulmonary infections and manifestations related to the ongoing COVID-19 pandemic. Coronaviruses are potentially neurotropic, which renders neuronal tissue vulnerable to infection, especially in elderly individuals or in those with neuro-comorbid conditions. Complaints of ageusia, anosmia, myalgia, and headache; reports of diseases such as stroke, encephalopathy, seizure, and encephalitis; and loss of consciousness in patients with COVID-19 confirm the neuropathophysiological aspect of this disease. The brain is linked to pulmonary organs, physiologically through blood circulation, and functionally through the nervous system. The interdependence of these vital organs may further aggravate the pathophysiological aspects of COVID-19. The induction of a cytokine storm in systemic circulation can trigger a neuroinflammatory cascade, which can subsequently compromise the blood-brain barrier and activate microglia- and astrocyte-borne Toll-like receptors, thereby leading to neuronal tissue damage. Hence, a holistic approach should be adopted by healthcare professionals while treating COVID-19 patients with a history of neurodegenerative disorders, neuropsychological complications, or any other neuro-compromised conditions. Imperatively, vaccines are being developed at top priority to contain the spread of the severe acute respiratory syndrome coronavirus 2, and different vaccines are at different stages of development globally. This review discusses the concerns regarding the neuronal complications of COVID-19 and the possible mechanisms of amelioration.

Biomaterials-assisted spheroid engineering for regenerative therapy

Cell-based therapy is a promising approach in the field of regenerative medicine. As cells are formed into spheroids, their survival, functions, and engraftment in the transplanted site are significantly improved compared to single cell transplantation. To improve the therapeutic effect of cell spheroids even further, various biomaterials (e.g., nano- or microparticles, fibers, and hydrogels) have been developed for spheroid engineering. These biomaterials not only can control the overall spheroid formation (e.g., size, shape, aggregation speed, and degree of compaction), but also can regulate cell-to-cell and cell-to-matrix interactions in spheroids. Therefore, cell spheroids in synergy with biomaterials have recently emerged for cell-based regenerative therapy. Biomaterials-assisted spheroid engineering has been extensively studied for regeneration of bone or/and cartilage defects, critical limb ischemia, and myocardial infarction. Furthermore, it has been expanded to pancreas islets and hair follicle transplantation. This paper comprehensively reviews biomaterials-assisted spheroid engineering for regenerative therapy. [BMB Reports 2021; 54(7): 356-367].

Combining stem cells in myocardial infarction: The road to superior repair?

Myocardial infarction irreversibly destroys millions of cardiomyocytes in the ventricle, making it the leading cause of heart failure worldwide. Over the past two decades, many progenitor and stem cell types were proposed as the ideal candidate to regenerate the heart after injury. The potential of stem cell therapy has been investigated thoroughly in animal and human studies, aiming at cardiac repair by true tissue replacement, by immune modulation, or by the secretion of paracrine factors that stimulate endogenous repair processes. Despite some successful results in animal models, the outcome from clinical trials remains overall disappointing, largely due to the limited stem cell survival and retention after transplantation. Extensive interest was developed regarding the combinational use of stem cells and various priming strategies to improve the efficacy of regenerative cell therapy. In this review, we provide a critical discussion of the different stem cell types investigated in preclinical and clinical studies in the field of cardiac repair. Moreover, we give an update on the potential of stem cell combinations as well as preconditioning and explore the future promises of these novel regenerative strategies.

Photo-Polymerization Damage Protection by Hydrogen Sulfide Donors for 3D-Cell Culture Systems Optimization

Photo-polymerized hydrogels are ideally suited for stem-cell based tissue regeneration and three dimensional (3D) bioprinting because they can be highly biocompatible, injectable, easy to use, and their mechanical and physical properties can be controlled. However, photo-polymerization involves the use of potentially toxic photo-initiators, exposure to ultraviolet light radiation, formation of free radicals that trigger the cross-linking reaction, and other events whose effects on cells are not yet fully understood. The purpose of this study was to examine the effects of hydrogen sulfide (H₂S) in mitigating cellular toxicity of photo-polymerization caused to resident cells during the process of hydrogel formation. H₂S, which is the latest discovered member of the gasotransmitter family of gaseous signalling molecules, has a number of established beneficial properties, including cell protection from oxidative damage both directly (by acting as a scavenger molecule) and indirectly (by inducing the expression of anti-oxidant proteins in the cell). Cells were exposed to slow release H₂S treatment using pre-conditioning with glutathione-conjugated-garlic extract in order to mitigate toxicity during the photo-polymerization process of hydrogel formation. The protective effects of the H₂S treatment were evaluated in both an enzymatic model and a 3D cell culture system using cell viability as a quantitative indicator. The protective effect of H₂S treatment of cells is a promising approach to enhance cell survival in tissue engineering applications requiring photo-polymerized hydrogel scaffolds.

Induced pluripotent stem cell-derived mesenchymal stem cells deliver exogenous miR-105-5p via small extracellular vesicles to rejuvenate senescent nucleus pulposus cells and attenuate intervertebral disc degeneration

Background

Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) have emerged as a promising new therapeutic strategy for intervertebral disc degeneration (IVDD). However, the drawbacks of MSCs, including their invasive access, the donor age, and their limited proliferative capacity, hinder the quantity and quality of MSC-sEVs. Induced pluripotent stem cell-derived MSCs (iMSCs) provide an indefinite source of MSCs with well-defined phenotype and function. This study aimed to investigate the therapeutic effect of sEVs derived from iMSC (iMSC-sEVs) on IVDD and explore the underlying molecular mechanisms.

Methods

IVDD models were established by puncturing discs from the tails of rats. Then, iMSC-sEVs were injected into the punctured discs. The degeneration of punctured discs was assessed using MRI and HE and immunofluorescence staining. The age-related phenotypes were used to determine the effects of iMSC-sEVs on senescent nucleus pulposus cells (NPCs) in vitro. Western blotting was used to detect the expression of Sirt6. miRNA sequencing analysis was used to find miRNAs that potentially mediate the activation of Sirt6.

Results

After intradiscally injecting iMSC-sEVs, NPC senescence and IVDD were significantly improved. iMSC-sEVs could rejuvenate senescent NPCs and restore the age-related function by activating the Sirt6 pathway in vitro. Further, microRNA sequence analysis showed that iMSC-sEVs were highly enriched in miR-105-5p, which played a pivotal role in the iMSC-sEV-mediated therapeutic effect by downregulating the level of the cAMP-specific hydrolase PDE4D and could lead to Sirt6 activation.

Conclusion

iMSC-sEVs could rejuvenate the senescence of NPCs and attenuate the development of IVDD. iMSC-sEVs exerted their anti-ageing effects by delivering miR-105-5p to senescent NPCs and activating the Sirt6 pathway. Our findings indicate that iMSCs are a promising MSC candidate for obtaining sEVs on a large scale, while avoiding several defects related to the present applications of MSCs, and that iMSC-sEVs could be a novel cell-free therapeutic tool for the treatment of IVDD.

Transplanted Erythropoietin-Expressing Mesenchymal Stem Cells Promote Pro-survival Gene Expression and Protect Photoreceptors From Sodium Iodate-Induced Cytotoxicity in a Retinal Degeneration Model

Mesenchymal stem cells (MSC) are highly regarded as a potential treatment for retinal degenerative disorders like retinitis pigmentosa and age-related macular degeneration. However, donor cell heterogeneity and inconsistent protocols for transplantation have led to varied outcomes in clinical trials. We previously showed that genetically-modifying MSCs to express erythropoietin (MSC^EPO) improved its regenerative capabilities in vitro. Hence, in this study, we sought to prove its potential in vivo by transplanting MSCs^EPO in a rat retinal degeneration model and analyzing its retinal transcriptome using RNA-Seq. Firstly, MSCs^EPO were cultured and expanded before being intravitreally transplanted into the sodium iodate-induced model. After the procedure, electroretinography (ERG) was performed bi-weekly for 30 days. Histological analyses were performed after the ERG assessment. The retina was then harvested for RNA extraction. After mRNA-enrichment and library preparation, paired-end RNA-Seq was performed. Salmon and DESeq2 were used to process the output files. The generated dataset was then analyzed using over-representation (ORA), functional enrichment (GSEA), and pathway topology analysis tools (SPIA) to identify enrichment of key pathways in the experimental groups. The results showed that the MSC^EPO-treated group had detectable ERG waves (P <0.05), which were indicative of successful phototransduction. The stem cells were also successfully detected by immunohistochemistry 30 days after intravitreal transplantation. An initial over-representation analysis revealed a snapshot of immune-related pathways in all the groups but was mainly overexpressed in the MSC group. A subsequent GSEA and SPIA analysis later revealed enrichment in a large number of biological processes including phototransduction, regeneration, and cell death (P_adj <0.05). Based on these pathways, a set of pro-survival gene expressions were extracted and tabulated. This study provided an in-depth transcriptomic analysis on the MSC^EPO-treated retinal degeneration model as well as a profile of pro-survival genes that can be used as candidates for further genetic enhancement studies on stem cells.

Investigating the effects of IDO1, PTGS2, and TGF-β1 overexpression on immunomodulatory properties of hTERT-MSCs and their extracellular vesicles

The therapeutic potential of mesenchymal stem cells (MSCs) is out of the question. Yet, recent drawbacks have resulted in a strategic shift towards the application of MSC-derived cell-free products such as extracellular vesicles (EVs). Recent reports revealed that functional properties of MSCs, including EV secretion patterns, correlate with microenvironmental cues. These findings highlight the urgent need for defining the optimal circumstances for EV preparation. Considering the limitations of primary cells, we employed immortalized cells as an alternative source to prepare therapeutically sufficient EV numbers. Herein, the effects of different conditional environments are explored on human TERT-immortalized MSCs (hTERT-MSCs). The latter were transduced to overexpress IDO1, PTGS2, and TGF-β1 transgenes either alone or in combination, and their immunomodulatory properties were analyzed thereafter. Likewise, EVs derived from these various MSCs were extensively characterized. hTERT-MSCs-IDO1 exerted superior inhibitory effects on lymphocytes, significantly more than hTERT-MSCs-IFN-γ. As such, IDO1 overexpression promoted the immunomodulatory properties of such enriched EVs. Considering the limitations of cell therapy like tumor formation and possible immune responses in the host, the results presented herein might be considered as a feasible model for the induction of immunomodulation in off-the-shelf and cell-free therapeutics, especially for autoimmune diseases.

Mechanical stretch promotes antioxidant responses and cardiomyogenic differentiation in P19 cells

Accumulating evidence has suggested that mechanical stimuli play a crucial role in regulating the lineage-specific differentiation of stem cells through fine-tuning redox balance. We aimed to investigate the effects of cyclic tensile strain (CTS) on the expression of antioxidant enzymes and cardiac-specific genes in P19 cells, a widely characterized tool for cardiac differentiation research. A stretching device was applied to generate different magnitude and duration of cyclic strains on P19 cells. The messenger RNA and protein levels of targeted genes were determined by real-time polymerase chain reaction and Western blot assays, respectively. Proper magnitude and duration of cognitive stimulation therapy (CST) stimulation substantially enhanced the expression of both antioxidant enzymes and cardiac-specific genes in P19 cells. Sirtuin 1 (SIRT1) played an essential role in the CTS-induced cardiomyogenic differentiation of P19, as evidenced by changes in the expression of antioxidant enzymes and cardiac-specific genes. Mechanical loading promoted the cardiomyogenic differentiation of P19 cells. SIRT1 was involved in CST-mediated P19 differentiation, implying that SIRT1 might serve as an important target for developing methods to promote cardiomyogenic differentiation of stem cells.

Non-Coding RNAs Steering the Senescence-Related Progress, Properties, and Application of Mesenchymal Stem Cells

The thirst to postpone and even reverse aging progress has never been quenched after all these decades. Unequivocally, mesenchymal stem cells (MSCs), with extraordinary abilities such as self-renewal and multi-directional differentiation, deserve the limelight in this topic. Though having several affable clinical traits, MSCs going through senescence would, on one hand, contribute to age-related diseases and, on the other hand, lead to compromised or even counterproductive therapeutical outcomes. Notably, increasing evidence suggests that non-coding RNAs (ncRNAs) could invigorate various regulatory processes. With even a slight dip or an uptick of expression, ncRNAs would make a dent in or even overturn cellular fate. Thereby, a systematic illustration of ncRNAs identified so far to steer MSCs during senescence is axiomatically an urgent need. In this review, we introduce the general properties and mechanisms of senescence and its relationship with MSCs and illustrate the ncRNAs playing a role in the cellular senescence of MSCs. It is then followed by the elucidation of ncRNAs embodied in extracellular vesicles connecting senescent MSCs with other cells and diversified processes in and beyond the skeletal system. Last, we provide a glimpse into the clinical methodologies of ncRNA-based therapies in MSC-related fields. Hopefully, the intricate relationship between senescence and MSCs will be revealed one day and our work could be a crucial stepping-stone toward that future.

'Primed' Mesenchymal Stem Cells: a Potential Novel Therapeutic for COVID19 Patients

The COVID19 pandemic, designated as a public health crisis by the World Health Organization (WHO), is rapidly spreading around the world impacting the health and economy of almost all the countries. The data of hospitalized COVID19 patients, especially those with serious illness, indicate the involvement of immunopathological complications. As no effective treatment is currently available, we propose ‘Primed’ Mesenchymal Stem Cells (MSCs) as a therapeutic alternative to tackle devastating epidemic. The individual response to MSCs treatment is heterogeneous. During the treatment of infectious pathology, the effectiveness of the treatment may vary based on the disease scenario. Interestingly, when transplanted in vivo, MSCs are governed by the locally regulated microenvironment, suggesting that the restorative variability could be tailored by choosing a priming regimen to specifically correct a given pathology. Therefore, in our opinion, the priming of MSCs could be a novel approach to improve the responses of COVID19 patients.

Ex vivo Ikkβ ablation rescues the immunopotency of mesenchymal stromal cells from diabetics with advanced atherosclerosis

AIMS

Diabetes is a conventional risk factor for atherosclerotic cardiovascular disease and myocardial infarction (MI) is the most common cause of death among these patients. Mesenchymal stromal cells (MSCs) in patients with type 2 diabetes mellitus (T2DM) and atherosclerosis have impaired ability to suppress activated T-cells (i.e. reduced immunopotency). This is mediated by an inflammatory shift in MSC-secreted soluble factors (i.e. pro-inflammatory secretome) and can contribute to the reduced therapeutic effects of autologous T2DM and atherosclerosis-MSC post-MI. The signalling pathways driving the altered secretome of atherosclerosis- and T2DM-MSC are unknown. Specifically, the effect of IκB kinase β (IKKβ) modulation, a key regulator of inflammatory responses, on the immunopotency of MSCs from T2DM patients with advanced atherosclerosis has not been studied.

METHODS AND RESULTS

MSCs were isolated from adipose tissue obtained from patients with (i) atherosclerosis and T2DM (atherosclerosis+T2DM MSCs, n = 17) and (ii) atherosclerosis without T2DM (atherosclerosis MSCs, n = 17). MSCs from atherosclerosis+T2DM individuals displayed an inflammatory senescent phenotype and constitutively expressed active forms of effectors of the canonical IKKβ nuclear factor-κB transcription factors inflammatory pathway. Importantly, this constitutive pro-inflammatory IKKβ signature resulted in an altered secretome and impaired in vitro immunopotency and in vivo healing capacity in an acute MI model. Notably, treatment with a selective IKKβ inhibitor or IKKβ knockdown (KD) (clustered regularly interspaced short palindromic repeats/Cas9-mediated IKKβ KD) in atherosclerosis+T2DM MSCs reduced the production of pro-inflammatory secretome, increased survival, and rescued their immunopotency both in vitro and in vivo.

CONCLUSIONS

Constitutively active IKKβ reduces the immunopotency of atherosclerosis+T2DM MSC by changing their secretome composition. Modulation of IKKβ in atherosclerosis+T2DM MSCs enhances their myocardial repair ability.

Human Mesenchymal Stem Cells for Spinal Cord Injury

Spinal Cord Injury (SCI), as a devastating and life-altering neurological disorder, is one of the most serious health issues. Currently, the management of acute SCI includes pharmacotherapy and surgical decompression. Both the approaches have been observed to have adverse physiological effects on SCI patients. Therefore, novel therapeutic targets for the management of SCI are urgently required for developing cell-based therapies. Multipotent stem cells, as a novel strategy for the treatment of tissue injury, may provide an effective therapeutic option against many neurological disorders. Mesenchymal stem cells (MSCs) or multipotent stromal cells can typically self-renew and generate various cell types. These cells are often isolated from bone marrow (BM-MSCs), adipose tissues (AD-MSCs), umbilical cord blood (UCB-MSCs), and placenta (PMSCs). MSCs have remarkable potential for the development of regenerative therapies in animal models and humans with SCI. Herein, we summarize the therapeutic potential of human MSCs in the treatment of SCI.

Smoking and Physical Activity Significantly Influence Stromal Vascular Fraction Cell Yield and Viability

BACKGROUND

Subcutaneous tissue is an abundant source of adipose-derived regenerative cells. It is readily available and easy to extract by means of liposuction, making it one of the most popular sources for tissue engineering and regenerative medical applications.

METHODS

The stromal vascular fraction (SVF) cell yield and viability of the lipoaspirate obtained from 43 patients undergoing elective liposuction were examined in correlation with their age, gender, body mass index, smoking status, and physical activity. The lipoaspirate was processed with the Celution^® 800/CRS system to isolate the SVF and a few drops of the obtained pellet were used for cell counting with NecleoCounter^® NC-100^TM.

RESULTS

Twenty-eight (65.1%) were men and 15 (34.9%) were women with an average age of 40.7 ± 10.4 years (women) and 38.9 ± 11.8 years (men). Viable SVF cells/g fat was significantly correlated with smoking level (negative correlation, ρ=  - 0.312, P < 0.05) and with marginal significance with female gender. Cell viability showed a significant negative correlation with physical activity level (ρ =   - 0.432, P < 0.01); borderline significance for correlation of this parameter with smoking level should not be neglected. Other parameters did not influence the cell yield nor the viability of the stromal vascular fraction.

CONCLUSION

Many factors may influence SVF cell yield and viability. Our findings indicate that age and smoking significantly influenced SVF cell yield, age positively while smoking negatively. Increased physical activity had a negative correlation with SVF cell viability.

LEVEL OF EVIDENCE N/A

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Regenerative Medicine for Equine Musculoskeletal Diseases

Simple Summary

Lameness due to musculoskeletal disease is the most common diagnosis in equine veterinary practice. Many of these orthopaedic disorders are chronic problems, for which no clinically satisfactory treatment exists. Thus, high hopes are pinned on regenerative medicine, which aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. Some regenerative medicine therapies have already made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising but diverse results. This review summarises the current knowledge of commonly used regenerative medicine treatments and critically discusses their use.

Abstract

Musculoskeletal injuries and chronic degenerative diseases commonly affect both athletic and sedentary horses and can entail the end of their athletic careers. The ensuing repair processes frequently do not yield fully functional regeneration of the injured tissues but biomechanically inferior scar or replacement tissue, causing high reinjury rates, degenerative disease progression and chronic morbidity. Regenerative medicine is an emerging, rapidly evolving branch of translational medicine that aims to replace or regenerate cells, tissues, or organs to restore or establish normal function. It includes tissue engineering but also cell-based and cell-free stimulation of endogenous self-repair mechanisms. Some regenerative medicine therapies have made their way into equine clinical practice mainly to treat tendon injures, tendinopathies, cartilage injuries and degenerative joint disorders with promising results. However, the qualitative and quantitative spatiotemporal requirements for specific bioactive factors to trigger tissue regeneration in the injury response are still unknown, and consequently, therapeutic approaches and treatment results are diverse. To exploit the full potential of this burgeoning field of medicine, further research will be required and is ongoing. This review summarises the current knowledge of commonly used regenerative medicine treatments in equine patients and critically discusses their use.

Human umbilical cord perivascular cells maintain regenerative traits following exposure to cyclophosphamide

Chemotherapies can cause germ cell depletion and gonadal failure. When injected post-chemotherapy, mesenchymal stromal cells (MSCs) from various sources have been shown to have regenerative effects in rodent models of chemotherapy-induced gonadal injury. Here, we evaluated two properties of a novel source of MSC, first trimester (FTM) human umbilical cord perivascular cells (HUCPVCs) (with increased regenerative potential compared to older sources), that may render them a promising candidate for chemotherapeutic gonadal injury prevention. Firstly, their ability to resist the cytotoxic effects of cyclophosphamide (CTX) in vitro, as compared to term HUCPVCs and bone marrow cells (BMSCs); and secondly, whether they prevent gonadal dysfunction if delivered prior to gonadotoxic therapy in vivo. BMSC, FTM HUCPVC, term HUCPVC, and control NTERA2 cells were treated with moderate (150 μmol/L) and high (300 μmol/L) doses of CTX in vitro. Viability, proliferative capacity, mesenchymal cell lineage markers and differentiation capacity, immunogenicity, and paracrine gene expression were assessed. CTX was administered to Wistar rats 2 days following an intra-ovarian injection of FTM HUCPVC. HUCPVC survival and ovarian follicle numbers were assessed using histological methods. We conclude that FTM HUCPVC maintain key regenerative properties following chemotherapy exposure and that pre-treatment with these cells may prevent CTX-induced ovarian damage in vivo. Therefore, HUCPVCs are promising candidates for fertility preservation.

Enhanced viability and function of mesenchymal stromal cell spheroids is mediated via autophagy induction

Mesenchymal stromal cells (MSCs) have received attention as promising therapeutic agents for the treatment of various diseases. However, poor post-transplantation viability is a major hurdle in MSC-based therapy, despite encouraging results in many inflammatory disorders. Recently, three dimensional (3D)-cultured MSCs (MSC_3D) were shown to have higher cell survival and enhanced anti-inflammatory effects, although the underlying mechanisms have not yet been elucidated. In this study, we investigated the molecular mechanisms by which MSC_3D gain the potential for enhanced cell viability. Herein, we found that macroautophagy/autophagy was highly induced and ROS production was suppressed in MSC_3D as compared to 2D-cultured MSCs (MSC_2D). Interestingly, inhibition of autophagy induction caused decreased cell viability and increased apoptotic activity in MSC_3D. Furthermore, modulation of ROS production was closely related to the survival and apoptosis of MSC_3D. We also observed that HMOX1 (heme oxygenase 1) was significantly up-regulated in MSC_3D. In addition, gene silencing of HMOX1 caused upregulation of ROS production and suppression of the genes related to autophagy. Moreover, inhibition of HIF1A (hypoxia inducible factor 1 subunit alpha) caused suppression of HMOX1 expression in MSC_3D, indicating that the HIF1A-HMOX1 axis plays a crucial role in the modulation of ROS production and autophagy induction in MSC_3D. Finally, the critical role of autophagy induction on improved therapeutic effects of MSC_3D was further verified in dextran sulfate sodium (DSS)-induced murine colitis. Taken together, these results indicated that autophagy activation and modulation of ROS production mediated via the HIF1A-HMOX1 axis play pivotal roles in enhancing the viability of MSC_3D.List of abbreviations:3D: three dimensional; 3MA: 3 methlyadenine; AMPK: AMP-activated protein kinase; Baf A₁: bafilomycin A₁; CFSE: carboxyfluorescein succinimidyl ester; CoCl₂: cobalt chloride; CoPP: cobalt protoporphyrin; DSS: dextran sulfate sodium; ECM: extracellular matrix; FOXO3/FOXO3A: forkhead box O3; HIF1A: hypoxia inducible factor 1 subunit alpha; HMOX1/HO-1: heme oxygenase 1; HSCs: hematopoietic stem cells; IL1A/IL-1α: interleukin 1 alpha; IL1B/IL-1β: interleukin 1 beta; IL8: interleukin 8; KEAP1: kelch like ECH associated protein 1; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; MSC_2D: 2D-cultured MSCs; MSC_3D: 3D-cultured MSCs; MSCs: mesenchymal stromal cells; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; PGE2: prostaglandin E2; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PINK1: PTEN induced kinase 1; ROS: reactive oxygen species; siRNA: small interfering RNA; SIRT1: sirtuin 1; SOD2: superoxide dismutase 2; SQSTM1/p62: sequestosome 1; TGFB/TGF-β: transforming growth factor beta.

TNFR2 Is a Crucial Hub Controlling Mesenchymal Stem Cell Biological and Functional Properties

Mesenchymal stem cells (MSCs) have drawn lots of attention as gold standard stem cells in fundamental and clinical researches during the last 20 years. Due to their tissue and vascular repair capacities, MSCs have been used to treat a variety of degenerative disorders. Moreover, MSCs are able to modulate immune cells’ functions, particularly T cells while inducing regulatory T cells (iTregs). MSCs are very sensitive to inflammatory signals. Their biological functions could remarkably vary after exposure to different pro-inflammatory cytokines, notably TNFα. In this article, we have explored the importance of TNFR2 expression in a series of MSCs’ biological and functional properties. Thus, MSCs from wild-type (WT) and TNFR2 knockout (TNFR2 KO) mice were isolated and underwent several ex vivo experiments to investigate the biological significance of TNFR2 molecule in MSC main functions. Hampering in TNFR2 signaling resulted in reduced MSC colony-forming units and proliferation rate and diminished the expression of all MSC characteristic markers such as stem cell antigen-1 (Sca1), CD90, CD105, CD44, and CD73. TNFR2 KO-MSCs produced more pro-inflammatory cytokines like TNFα, IFNγ, and IL-6 and less anti-inflammatory mediators such as IL-10, TGFβ, and NO and induced Tregs with less suppressive effect. Furthermore, the TNFR2 blockade remarkably decreased MSC regenerative functions such as wound healing, complex tube formation, and endothelial pro-angiogenic support. Therefore, our results reveal the TNFα–TNFR2 axis as a crucial regulator of MSC immunological and regenerative functions.

Extracellular matrix-based biomaterials as adipose-derived stem cell delivery vehicles in wound healing: a comparative study between a collagen scaffold and two xenografts

BACKGROUND

Stem cell therapies represent a promising tool in regenerative medicine. Considering the drawbacks of direct stem cell injections (e.g. poor cell localisation), extracellular matrix-based biomaterials (e.g. scaffolds and tissue grafts), due to their compositional biofunctionality and cytocompatibility, are under investigation as potential stem cell carriers.

METHODS

The present study assessed the potential of three commercially available extracellular matrix-based biomaterials [a collagen/glycosaminoglycan scaffold (Integra™ Matrix Wound Dressing), a decellularised porcine peritoneum (XenoMEM™) and a porcine urinary bladder (MatriStem™)] as human adipose-derived stem cell delivery vehicles.

RESULTS

Both tissue grafts induced significantly (p < 0.01) higher human adipose-derived stem cell proliferation in vitro over the collagen scaffold, especially when the cells were seeded on the basement membrane side. Human adipose-derived stem cell phenotype and trilineage differentiation potential was preserved in all biomaterials. In a splinted wound healing nude mouse model, in comparison to sham, biomaterials alone and cells alone groups, all biomaterials seeded with human adipose-derived stem cells showed a moderate improvement of wound closure, a significantly (p < 0.05) lower wound gap and scar index and a significantly (p < 0.05) higher proportion of mature collagen deposition and angiogenesis (the highest, p < 0.01, was observed for the cell loaded at the basement membrane XenoMEM™ group). All cell-loaded biomaterial groups retained more cells at the implantation side than the direct injection group, even though they were loaded with half of the cells than the cell injection group.

CONCLUSIONS

This study further advocates the use of extracellular matrix-based biomaterials (in particular porcine peritoneum) as human adipose-derived stem cell delivery vehicles. Comparative analysis of a collagen scaffold (Integra™ Matrix Wound Dressing) and two tissue grafts [decellularised porcine peritoneum (XenoMEM™) and porcine urinary bladder (MatriStem™)] as human adipose-derived stem cells carriers.

The role of mesenchymal stem/stromal cells in the acute clinical setting

INTRODUCTION

Accumulating evidence supports the use of mesenchymal stem/stromal cells (MSCs), particularly bone marrow derived, as a safe and promising biologic therapy for promoting tissue repair and regeneration in various chronic diseases and disorders. Despite growing evidence that MSCs are potent anti-inflammatory mediators that can provide substantial benefits in acute organ injury, there are limited clinical trials utilizing MSCs in acute care settings, such as in the emergency department (ED) or intensive care unit (ICU).

OBJECTIVE

This article reviews the current state of MSC-based therapeutics and further explores the untapped potential role to treat various acute, life-threating injuries in the ED and ICU.

DISCUSSION

All clinical trials using MSCs in acute myocardial infarction (AMI), acute respiratory distress syndrome (ARDS), sepsis and acute kidney injury (AKI) demonstrated safety. While some also demonstrate clinical efficacy, efficacy data is inconsistent, with some studies limited by sample size, cell integrity and different dosages, necessitating further studies.

CONCLUSION

MSCs are potentially promising novel biologic therapeutics for clinical application in AMI, ARDS, sepsis, AKI and COVID-19 that have demonstrated safety in all clinical trials. More rigorous clinical trials are necessary and warranted to determine the efficacy of MSCs as a novel therapeutic in an acute setting, such as the ED.

Injectable Hydrogels as Three-Dimensional Network Reservoirs for Osteoporosis Treatment

Despite tremendous progresses made in the field of tissue engineering over the past several decades, it remains a significant challenge for the treatment of osteoporosis (OP) due to the lack of appropriate carriers to improve the bioavailability of therapeutic agents and the unavailability of artificial bone matrix with desired properties for the replacement of damaged bone regions. Encouragingly, the development of injectable hydrogels for the treatment of OP has attracted increasing attention in recent years because they can serve either as a reservoir for various therapeutic species or as a perfect filler for bone injuries with irregular shapes. However, the relationship between the complicated pathological mechanism of OP and the properties of diverse polymeric materials lacks elucidation, which clearly hampers the clinical application of injectable hydrogels for the efficient treatment of OP. To clarify this relationship, this article summarized both localized and systematic treatment of OP using an injectable hydrogel-based strategy. Specifically, the pathogenesis of OP and the limitations of current treatment approaches were first analyzed. We further focused on the use of hydrogels loaded with various therapeutic substances following a classification standard of the encapsulated cargoes for OP treatment with an emphasis on the application and precautions of each category. A concluding remark on existing challenges and future directions of this rapidly developing research area was finally made. Impact statement Effective osteoporosis (OP) treatment remains a significant challenge due substantially to the unavailability of appropriate drug carriers and artificial matrices with desired properties to promote bone repair and replace damaged regions. For this purpose, this review focused on the development of diverse injectable hydrogel systems for the delivery of various therapeutic agents, including drugs, stem cells, and nucleic acids, for effective increase in bone mass and favorable osteogenesis. The summarized important guidelines are believed to promote clinical development and translation of hydrogels for the efficient treatment of OP and OP-related bone damages toward improved life quality of millions of patients.

Regenerative medicine approaches for the management of respiratory tract fistulas

Respiratory tract fistulas (or fistulae) are abnormal communications between the respiratory system and the digestive tract or the adjacent organs. The origin can be congenital or, more frequently, iatrogenic and the clinical presentation is heterogeneous. Respiratory tract fistulas can lead to severely reduced health-related quality of life and short survival. Therapy mainly relies on endoscopic surgical interventions but patients often require prolonged hospitalization and may develop complications. Therefore, more conservative regenerative medicine approaches, mainly based on lipotransfer, have also been investigated. Adipose tissue can be delivered either as unprocessed tissue, or after enzymatic treatment to derive the cellular stromal vascular fraction. In the current narrative review, we provide an overview of the main tissue/cell-based clinical studies for the management of various types of respiratory tract fistulas or injuries. Clinical experience is limited, as most of the studies were performed on a small number of patients. Albeit a conclusive proof of efficacy cannot be drawn, the reviewed studies suggest that grafting of adipose tissue-derived material may represent a minimally invasive and conservative treatment option, alternative to more aggressive surgical procedures. Knowledge on safety and tolerability acquired in prior studies can lead to the design of future, larger trials that may exploit innovative procedures for tissue processing to further improve the clinical outcome.

Angiogenic biomaterials to promote therapeutic regeneration and investigate disease progression

The vasculature is a key component of the tissue microenvironment. Traditionally known for its role in providing nutrients and oxygen to surrounding cells, the vasculature is now also acknowledged to provide signaling cues that influence biological outcomes in regeneration and disease. These cues come from the cells that comprise vasculature, as well as the dynamic biophysical and biochemical properties of the surrounding extracellular matrix that accompany vascular development and remodeling. In this review, we illustrate the larger role of the vasculature in the context of regenerative biology and cancer progression. We describe cellular, biophysical, biochemical, and metabolic components of vascularized microenvironments. Moreover, we provide an overview of multidimensional angiogenic biomaterials that have been developed to promote therapeutic vascularization and regeneration, as well as to mimic elements of vascularized microenvironments as a means to uncover mechanisms by which vasculature influences cancer progression and therapy.

Photoluminescent oxygen-release microspheres to image the oxygen release process in vivo

Cell therapy is a promising strategy to treat ischemic diseases, but the efficacy is limited due to high rate of cell death under low oxygen environment of the ischemic tissues. Sustained release of oxygen to continuously oxygenate the transplanted cells may augment cell survival and improve therapeutic efficacy. We have shown previously that oxygen released from oxygen-release microspheres stimulated cell survival in ischemic tissue [1]. To understand how oxygen is released in vivo and duration of release, it is attractive to image the process of oxygen release. Herein, we have developed photoluminenscent oxygen-release microspheres where the in vivo oxygen release can be non-invasively and real-time monitored by an In Vivo Imaging System (IVIS). In the oxygen-release microspheres, a complex of polyvinylpyrrolidone, H₂O₂ and a fluorescent drug hypericin (HYP) was used as core, and poly(N-isopropylacrylamide-co-acrylate-oligolactide-co-hydroxyethyl methacrylate-co-N-acryloxysuccinimide) conjugated with catalase was used as shell. To distinguish fluorescent signal change for different oxygen release kinetics, the microspheres with various release profiles were developed by using the shell with different degradation rates. In vitro, the fluorescent intensity gradually decreased during the 21-day oxygen release period, consistent with oxygen release kinetics. The released oxygen significantly augmented mesenchymal stem cell (MSC) survival under hypoxic condition. In vivo, the oxygen release rate was faster. The fluorescent signal can be detected for 17 days for the microspheres with the slowest oxygen release kinetics. The implanted microspheres did not induce substantial inflammation. The above results demonstrate that the developed microspheres have potential to monitor the in vivo oxygen release.

Mesenchymal Stem Cell Secretome as an Emerging Cell-Free Alternative for Improving Wound Repair

The use of mesenchymal stem cells (MSC) for the treatment of cutaneous wounds is currently of enormous interest. However, the broad translation of cell therapies into clinical use is hampered by their efficacy, safety, manufacturing and cost. MSCs release a broad repertoire of trophic factors and immunomodulatory cytokines, referred to as the MSC secretome, that has considerable potential for the treatment of cutaneous wounds as a cell-free therapy. In this review, we outline the current status of MSCs as a treatment for cutaneous wounds and introduce the potential of the MSC secretome as a cell-free alternative for wound repair. We discuss the challenges and provide insights and perspectives for the future development of the MSC secretome as well as identify its potential clinical translation into a therapeutic treatment.

Ultrasound Therapy: Experiences and Perspectives for Regenerative Medicine

Ultrasound has emerged as a novel tool for clinical applications, particularly in the context of regenerative medicine. Due to its unique physico-mechanical properties, low-intensity ultrasound (LIUS) has been approved for accelerated fracture healing and for the treatment of established non-union, but its utility has extended beyond tissue engineering to other fields, including cell regeneration. Cells and tissues respond to acoustic ultrasound by switching on genetic repair circuits, triggering a cascade of molecular signals that promote cell proliferation, adhesion, migration, differentiation, and extracellular matrix production. LIUS also induces angiogenesis and tissue regeneration and has anti-inflammatory and anti-degenerative effects. Accordingly, the potential application of ultrasound for tissue repair/regeneration has been tested in several studies as a stand-alone treatment and, more recently, as an adjunct to cell-based therapies. For example, ultrasound has been proposed to improve stem cell homing to target tissues due to its ability to create a transitional and local gradient of cytokines and chemokines. In this review, we provide an overview of the many applications of ultrasound in clinical medicine, with a focus on its value as an adjunct to cell-based interventions. Finally, we discuss the various preclinical and clinical studies that have investigated the potential of ultrasound for regenerative medicine.

Glucocorticoid Priming of Nonviral Gene Delivery to hMSCs Increases Transfection by Reducing Induced Stresses

Human mesenchymal stem cells (hMSCs) are under study for cell and gene therapeutics because of their immunomodulatory and regenerative properties. Safe and efficient gene delivery could increase hMSC clinical potential by enabling expression of transgenes for control over factor production, behavior, and differentiation. Viral delivery is efficient but suffers from safety issues, while nonviral methods are safe but highly inefficient, especially in hMSCs. We previously demonstrated that priming cells with glucocorticoids (Gcs) before delivery of DNA complexes significantly increases hMSC transfection, which correlates with a rescue of transfection-induced metabolic and protein synthesis decline, and apoptosis. In this work, we show that transgene expression enhancement is mediated by transcriptional activation of endogenous hMSC genes by the cytosolic glucocorticoid receptor (cGR) and that transfection enhancement can be potentiated with a GR transcription-activation synergist. We demonstrate that the Gc-activated cGR modulates endogenous hMSC gene expression to ameliorate transfection-induced endoplasmic reticulum (ER) and oxidative stresses, apoptosis, and inflammatory responses to prevent hMSC metabolic and protein synthesis decline, resulting in enhanced transgene expression after nonviral gene delivery to hMSCs. These results provide insights important for rational design of more efficient nonviral gene delivery and priming techniques that could be utilized for clinical hMSC applications.

Conductive carbon nanofibers incorporated into collagen bio-scaffold assists myocardial injury repair

Currently, treatment of myocardial infarction considered as unmet clinical need. Nanomaterials have been used in the regeneration of tissues such as bone, dental and neural tissue in the body and have increased hope for revitalizing of damaged tissues. Conductive carbon base nanomaterials with its superior physicochemical properties have emerged as promising materials for cardiovascular application. In this study, we applied a biosynthetic collagen scaffold containing carbon nanofiber for regenerating of damaged heart tissue. The collagen-carbon nanofiber scaffold was fabricated and fully characterised. The scaffold was grafted on the affected area of myocardial ischemia, immediately after ligation of the left anterior descending artery in the wistar rat's model. After 4 weeks, histological analyses were performed for investigation of formation of immature cardio-myocytes, epicardial cells, and angiogenesis. Compared to untreated hearts, this scaffold significantly protects heart tissue against injury. This improvement is accompanied by a reduction in fibrosis and the increased formation of a blood vessel network and immature cardio-myocytes in the infarction heart. No toxicity detected with apoptotic and TUNEL assays. In conclusion, the mechanical support of the collagen scaffold with carbon nanofiber enhanced the regeneration of myocardial tissue.

Mitochondria transfer enhances proliferation, migration, and osteogenic differentiation of bone marrow mesenchymal stem cell and promotes bone defect healing

Background

Bone marrow-derived mesenchymal stem cell (BMSC) transplantation is considered a promising therapeutic approach for bone defect repair. However, during the transplantation procedure, the functions and viability of BMSCs may be impaired due to extended durations of in vitro culture, aging, and disease conditions of patients. Inspired by spontaneous intercellular mitochondria transfer that naturally occurs within injured tissues to rescue cellular or tissue function, we investigated whether artificial mitochondria transfer into pre-transplant BMSCs in vitro could improve cellular function and enhance their therapeutic effects on bone defect repair in situ.

Methods

Mitochondria were isolated from donor BMSCs and transferred into recipient BMSCs of the same batch and passage. Subsequently, changes in proliferative capacity and cell senescence were evaluated by live cell imaging, Cell Counting Kit-8 assay, cell cycle analysis, Ki67 staining, qPCR and Western blot analysis of c-Myc expression, and β-galactosidase staining. Migration ability was evaluated by the transwell migration assay, wound scratch healing, and cell motility tests. Alkaline phosphatase (ALP) staining, Alizarin Red staining, and combined with qPCR and Western blot analyses of Runx2 and BMP2 were performed to elucidate the effects of mitochondria transfer on the osteogenic potential of BMSCs in vitro. After that, in vivo experiments were performed by transplanting mitochondria-recipient BMSCs into a rat cranial critical-size bone defect model. Micro CT scanning and histological analysis were conducted at 4 and 8 weeks after transplantation to evaluate osteogenesis in situ. Finally, in order to establish the correlation between cellular behavioral changes and aerobic metabolism, OXPHOS (oxidative phosphorylation) and ATP production were assessed and inhibition of aerobic respiration by oligomycin was performed.

Results

Mitochondria-recipient BMSCs exhibited significantly enhanced proliferation and migration, and increased osteogenesis upon osteogenic induction. The in vivo results showed more new bone formation after transplantation of mitochondria-recipient BMSCs in situ. Increased OXPHOS activity and ATP production were observed, which upon inhibition by oligomycin attenuated the enhancement of proliferation, migration, and osteogenic differentiation induced by mitochondria transfer.

Conclusions

Mitochondria transfer is a feasible technique to enhance BMSC function in vitro and promote bone defect repair in situ through the upregulation of aerobic metabolism. The results indicated that mitochondria transfer may be a novel promising technique for optimizing stem cell therapeutic function.

A novel role of vitronectin in promoting survival of mesenchymal stem cells under serum deprivation stress

Background

Due to their immunomodulatory and trophic support functions, mesenchymal stem cells (MSCs) are promising in the field of cell-based regenerative medicine. However, MSC survival post-transplantation is challenged by various microenvironment stress factors. Here, we investigated the role of vitronectin (VTN) in the survival strategy of MSCs under serum deprivation stress condition.

Methods

Proliferation kinetics and cell adhesion of MSCs under serum deprivation were determined from population doublings and cell-matrix de-adhesion studies, respectively. mRNA and protein expression levels of VTN were confirmed by qRT-PCR and Western blotting, respectively. Immunofluorescence technique revealed distribution of VTN under serum deprivation stress. siRNA and inhibitor-based studies were performed to confirm the role and regulation of VTN. Apoptosis and cell cycle status of MSCs were assessed using flow cytometric analysis.

Results

Subjecting MSCs to serum deprivation led to significant increase in cell spread area and cell-matrix adhesion. An upregulation of VTN expression was noted with an arrest in G0/G1 phase of cell cycle and no appreciable apoptotic change. Pro-survival PI3kinase pathway inhibition led to further increase in VTN expression with no apoptotic change. siRNA-mediated inhibition of VTN resulted in reversal in G0/G1 cell cycle arrest and a marked increase in apoptosis, suggesting a role of VTN in preventing serum deprivation-induced apoptotic cell death. In addition, p65 knockdown resulted in downregulation of VTN establishing an association between NF-κβ pathway and VTN.

Conclusions

VTN was identified as a survival factor in providing protection from serum deprivation-induced apoptosis in MSCs.

Alginate-encapsulated brain-derived neurotrophic factor-overexpressing mesenchymal stem cells are a promising drug delivery system for protection of auditory neurons

The cochlear implant outcome is possibly improved by brain-derived neurotrophic factor treatment protecting spiral ganglion neurons. Implantation of genetically modified mesenchymal stem cells may enable the required long-term brain-derived neurotrophic factor administration. Encapsulation of mesenchymal stem cells in ultra-high viscous alginate may protect the mesenchymal stem cells from the recipient’s immune system and prevent their uncontrolled migration. Alginate stability and survival of mesenchymal stem cells in alginate were evaluated. Brain-derived neurotrophic factor production was measured and its protective effect was analyzed in dissociated rat spiral ganglion neuron co-culture. Since the cochlear implant is an active electrode, alginate–mesenchymal stem cell samples were electrically stimulated and alginate stability and mesenchymal stem cell survival were investigated. Stability of ultra-high viscous-alginate and alginate–mesenchymal stem cells was proven. Brain-derived neurotrophic factor production was detectable and spiral ganglion neuron survival, bipolar morphology, and neurite outgrowth were increased. Moderate electrical stimulation did not affect the mesenchymal stem cell survival and their viability was good within the investigated time frame. Local drug delivery by ultra-high viscous-alginate-encapsulated brain-derived neurotrophic factor–overexpressing mesenchymal stem cells is a promising strategy to improve the cochlear implant outcome.

Current Status and Future Prospects of Genome-Scale Metabolic Modeling to Optimize the Use of Mesenchymal Stem Cells in Regenerative Medicine

Mesenchymal stem cells are a promising source for externally grown tissue replacements and patient-specific immunomodulatory treatments. This promise has not yet been fulfilled in part due to production scaling issues and the need to maintain the correct phenotype after re-implantation. One aspect of extracorporeal growth that may be manipulated to optimize cell growth and differentiation is metabolism. The metabolism of MSCs changes during and in response to differentiation and immunomodulatory changes. MSC metabolism may be linked to functional differences but how this occurs and influences MSC function remains unclear. Understanding how MSC metabolism relates to cell function is however important as metabolite availability and environmental circumstances in the body may affect the success of implantation. Genome-scale constraint based metabolic modeling can be used as a tool to fill gaps in knowledge of MSC metabolism, acting as a framework to integrate and understand various data types (e.g., genomic, transcriptomic and metabolomic). These approaches have long been used to optimize the growth and productivity of bacterial production systems and are being increasingly used to provide insights into human health research. Production of tissue for implantation using MSCs requires both optimized production of cell mass and the understanding of the patient and phenotype specific metabolic situation. This review considers the current knowledge of MSC metabolism and how it may be optimized along with the current and future uses of genome scale constraint based metabolic modeling to further this aim.

Altered Adhesion and Migration of Human Mesenchymal Stromal Cells under Febrile Temperature Stress Involves NF-κβ Pathway

Mesenchymal stromal cells (MSCs) are clinically beneficial for regenerative treatment of chronic inflammation and autoimmune disorders. However, to attain maximum efficacy from the transplanted MSCs, evaluation of its interaction with the microenvironment, becomes critical. Fever being an important hallmark of inflammation, we investigated the effect of febrile temperature stress on adhesion and migration of umbilical cord-derived MSCs. 40 °C-exposure altered cellular morphology with significant cell flattening, delayed cell-matrix de-adhesion response and slower migration of MSCs, accompanied by suppressed directionality ratio and cell trajectory. Corresponding to the observed changes, mRNA expression of extracellular matrix genes like COLs and VTN were upregulated, while matrix metalloproteinase MMP-1, showed a significant downregulation. NF-κβ pathway inhibition at 40 °C, led to reversal of gene expression pattern, cell spreading, de-adhesion dynamics and migration rate. Independent knockdown of p65 and p53 at 40 °C indicated inhibitory role of p65/p53/p21 axis in regulation of MMP-1 expression. P21 inhibits JNK activity, and JNK pathway inhibition at 40 °C resulted in further downregulation of MMP-1. Hence, our study provides the first evidence of cell migration getting adversely affected in MSCs under elevated temperature stress due to an inverse relationship between p65/p53/p21 and MMP1 with a possible involvement of the JNK pathway.

Mesenchymal Stem Cell Derived Extracellular Vesicles in Aging

Aging is associated with high prevalence of chronic degenerative diseases that take a large part of the increasing burden of morbidities in a growing demographic of elderly people. Aging is a complex process that involves cell autonomous and cell non-autonomous mechanisms where senescence plays an important role. Senescence is characterized by the loss of proliferative potential, resistance to cell death by apoptosis and expression of a senescence-associated secretory phenotype (SASP). SASP includes pro-inflammatory cytokines and chemokines, tissue-damaging proteases, growth factors; all contributing to tissue microenvironment alteration and loss of tissue homeostasis. Emerging evidence suggests that the changes in the number and composition of extracellular vesicles (EVs) released by senescent cells contribute to the adverse effects of senescence in aging. In addition, age-related alterations in mesenchymal stem/stromal cells (MSCs) have been associated to dysregulated functions. The loss of functional stem cells necessary to maintain tissue homeostasis likely directly contributes to aging. In this review, we will focus on the characteristics and role of EVs isolated from senescent MSCs, the potential effect of MSC-derived EVs in aging and discuss their therapeutic potential to improve age-related diseases.

Effects of human urine-derived stem cells on the cementogenic differentiation of indirectly-cocultured periodontal ligament stem cells

Human periodontal ligament stem cells (PDLSCs) have been widely applied as seed cells and cell sheets in periodontal tissue regeneration. Despite significant progress in PDLSCs application, it is a major challenge to promote cell proliferation and multiple differentiations of PDLSCs because cell numbers at the initial obtaining are limited. The goal of study was to determine the paracrine effects of human urine-derived stem cells (USCs) on cell proliferation and osteogenic differentiation of PDLSCs when USCs were indirectly-co-cultured with PDLSCs. After indirectly-co-cultured with USCs at different ratios (PDLSC/USC, 1/0.5, 1/1 and 1/2), number of PDLSCs among the three co-cultured groups visibly increased from day 5 to a similar extent, and the expression of osteogenic and cementogenic genes and proteins in the osteogenic medium significantly increased with an increasing proportion of USCs compared to USC-free control group. In addition, osteogenic matrix PDLSC sheets at a PDLSC/USC ratio of 1/2 contained denser collagen layers and exhibited increased osteogenic and cementogenic protein expression. In vivo transplantation showed that PDLSC sheets noncontact cocultured at a PDLSC/USC ratio of 1/2 formed more new and dense structures and expressed higher levels of osteogenic and cementogenic proteins. In conclusion, the present results demonstrate that USCs promote the proliferation and osteogenic and cementogenic differentiation of PDLSCs in a ratio-dependent manner through noncontact coculture and further accelerate the regeneration of new structures by osteogenic matrix PDLSC sheets in vivo. These results suggest their use as a new strategy for application in clinical periodontal tissue repair.

Modulation of the in vitro angiogenic potential of human mesenchymal stromal cells from different tissue sources

Mesenchymal stromal cells (MSCs) have been widely exploited for the treatment of several conditions due to their intrinsic regenerative and immunomodulatory properties. MSC have demonstrated to be particularly relevant for the treatment of ischemic diseases, where MSC-based therapies can stimulate angiogenesis and induce tissue regeneration. Regardless of the condition targeted, recent analyses of MSC-based clinical trials have demonstrated limited benefits indicating a need to improve the efficacy of this cell product. Preconditioning MSC ex vivo through microenvironment modulation was found to improve MSC survival rate and thus prolong their therapeutic effect. This workstudy aims at enhancing the in vitro angiogenic capacity of a potential MSC-based medicinal product by comparing different sources of MSC and culture conditions. MSC from three different sources (bone marrow [BM], adipose tissue [AT], and umbilical cord matrix [UCM]) were cultured with xenogeneic-/serum-free culture medium under static conditions and their angiogenic potential was studied. Results indicated a higher in vitro angiogenic capacity of UCM MSC, compared with cells derived from BM and AT. Physicochemical preconditioning of UCM MSC through a microcarrier-based culture platform and low oxygen concentration (2% O₂ , compared with atmospheric air) increased the in vitro angiogenic potential of the cultured cells. Envisaging the clinical manufacturing of an allogeneic, off-the-shelf MSC-based product, preconditioned UCM MSC maintain the angiogenic gene expression profile upon cryopreservation and delivery processes in the conditions of our study. These results are expected to contribute to the development of MSC-based therapies in the context of angiogenesis.

Comparative study of the production of soluble factors in human placenta-derived mesenchymal stromal/stem cells grown in adherent conditions or as aggregates in a catheter-like device

Different approaches have been studied in both preclinical and clinical settings to develop cell-based therapies and/or engineered cell-based therapies to better integrate grafts with the host. In these techniques, much attention is addressed to the use of adult stem cells such as mesenchymal stem cells (MSCs), but identifying and obtaining sufficient numbers of therapeutic cells, and the right route of administration, is often a challenge. In this study, we tested the feasibility of encapsulating human amnion-derived MSCs (hAMSCs) in a semipermeable and biocompatible fiber as a new approach for regenerative medicine. Our data showed that hAMSCs aggregated in the device constitutes an effective system for enhancing, or at least for maintaining, the paracrine activity of these cells in order to better promote tissue regeneration in an immune isolated state. In our new experimental approach, the hAMSCs retained their therapeutic potential, as shown by both the production of specific immunomodulatory/angiogenic factors and immunomodulatory and angiogenic ability observed in vitro. Unlike cell infusion methods, the use of encapsulated-cells leads to minimally invasive approaches, avoiding a direct interaction with the host. Therefore, the potentiality of an allograft or xenograft without the need for immunosuppression, and the lack of tumorigenesis is very intriguing.

Cladophora glomerata methanolic extract promotes chondrogenic gene expression and cartilage phenotype differentiation in equine adipose-derived mesenchymal stromal stem cells affected by metabolic syndrome

BACKGROUND

Chondrogenesis represents a highly dynamic cellular process that leads to the establishment of various types of cartilage. However, when stress-related injuries occur, a rapid and efficient regeneration of the tissues is necessary to maintain cartilage integrity. Mesenchymal stem cells (MSCs) are known to exhibit high capacity for self-renewal and pluripotency effects, and thus play a pivotal role in the repair and regeneration of damaged cartilage. On the other hand, the influence of certain pathological conditions such as metabolic disorders on MSCs can seriously impair their regenerative properties and thus reduce their therapeutic potential.

OBJECTIVES

In this investigation, we attempted to improve and potentiate the in vitro chondrogenic ability of adipose-derived mesenchymal stromal stem cells (ASCs) isolated from horses suffering from metabolic syndrome.

METHODS

Cultured cells in chondrogenic-inductive medium supplemented with Cladophora glomerata methanolic extract were experimented for expression of the main genes and microRNAs involved in the differentiation process using RT-PCR, for their morphological changes through confocal and scanning electron microscopy and for their physiological homeostasis.

RESULTS

The different added concentrations of C. glomerata extract to the basic chondrogenic inductive culture medium promoted the proliferation of equine metabolic syndrome ASCs (ASCsEMS) and resulted in chondrogenic phenotype differentiation and higher mRNA expression of collagen type II, aggrecan, cartilage oligomeric matrix protein, and Sox9 among others. The results reveal an obvious inhibitory effect of hypertrophy and a strong repression of miR-145-5p, miR-146-3p, and miR-34a and miR-449a largely involved in cartilage degradation. Treated cells additionally exhibited significant reduced apoptosis and oxidative stress, as well as promoted viability and mitochondrial potentiation.

CONCLUSION

Chondrogenesis in EqASCsEMS was found to be prominent after chondrogenic induction in conditions containing C. glomerata extract, suggesting that the macroalgae could be considered for the enhancement of ASC cultures and their reparative properties.

The biological response of mesenchymal stromal cells to thymol and carvacrol in comparison to their essential oil: An innovative new study

Mesenchymal stromal cells (MSCs) represent a progenitor cell population with several biological properties. MSCs are thus of therapeutic interest for cell-based therapy but great efforts are needed to enhance their efficiency and safety. Herbal remedies and in particular their bioactive molecules, are potential candidates for improving human health. The novelty and originality of this study is to develop an efficient cell-therapeutic product by combining MSCs with medicinal plant derived bioactive molecules. Thus, the impact of Essential Oil, Thymol and Carvacrol from Ptychotis verticillata on several BM-MSC biological features were studied. These compounds have shown positive effects on MSCs by preserving their morphology, sustaining their viability, promoting their proliferation, protecting them from cytotoxicity and oxidative stress. Accordingly, the combined administration of P. verticillata extract and MSCs may represent a new approach to enhance the therapeutic issue. Further investigations should greatly improve the manufacturing of these compounds as well as our understanding of the therapeutic effects of these bioactive molecules on the biology and functions of MSCs.

Intraoperative Strategies for Minimal Manipulation of Autologous Adipose Tissue for Cell- and Tissue-Based Therapies: Concise Review

The stromal vascular fraction (SVF) is a heterogeneous population of stem/stromal cells isolated from perivascular and extracellular matrix (ECM) of adipose tissue complex (ATC). Administration of SVF holds a strong therapeutic potential for regenerative and wound healing medicine applications aimed at functional restoration of tissues damaged by injuries or chronic diseases. SVF is commonly divided into cellular stromal vascular fraction (cSVF) and tissue stromal vascular fraction (tSVF). Cellular SVF is obtained from ATC by collagenase digestion, incubation/isolation, and pelletized by centrifugation. Enzymatic disaggregation may alter the relevant biological characteristics of adipose tissue, while providing release of complex, multiattachment of cell-to-cell and cell-to-matrix, effectively eliminating the bioactive ECM and periadventitial attachments. In many countries, the isolation of cellular elements is considered as a "more than minimal" manipulation, and is most often limited to controlled clinical trials and subject to regulatory review. Several alternative, nonenzymatic methods of adipose tissue processing have been developed to obtain via minimal mechanical manipulation an autologous tSVF product intended for delivery, reducing the procedure duration, lowering production costs, decreasing regulatory burden, and shortening the translation into the clinical setting. Ideally, these procedures might allow for the integration of harvesting and processing of adipose tissue for ease of injection, in a single procedure utilizing a nonexpanded cellular product at the point of care, while permitting intraoperative autologous cellular and tissue-based therapies. Here, we review and discuss the options, advantages, and limitations of the major strategies alternative to enzymatic processing currently developed for minimal manipulation of adipose tissue. Stem Cells Translational Medicine 2019;8:1265&1271.

The impact of cryopreservation on bone marrow-derived mesenchymal stem cells: a systematic review

Mesenchymal stem cells (MSCs) represent an invaluable asset for the field of cell therapy. Human Bone marrow-derived MSCs (hBM-MSCs) are one of the most commonly used cell types in clinical trials. They are currently being studied and tested for the treatment of a wide range of diseases and conditions. The future availability of MSCs therapies to the public will require a robust and reliable delivery process. Cryopreservation represents the gold standard in cell storage and transportation, but its effect on BM-MSCs is still not well established. A systematic review was conducted to evaluate the impact of cryopreservation on BM-MSCs and to attempt to uncover the reasons behind some of the controversial results reported in the literature. Forty-one in vitro studies were analysed, and their results organised according to the cell attributes they assess. It was concluded that cryopreservation does not affect BM-MSCs morphology, surface marker expression, differentiation or proliferation potential. However, mixed results exist regarding the effect on colony forming ability and the effects on viability, attachment and migration, genomic stability and paracrine function are undefined mainly due to the huge variabilities governing the cryopreservation process as a whole and to the lack of standardised assays.

Transplantation of Mouse Induced Pluripotent Stem Cell-Derived Podocytes in a Mouse Model of Membranous Nephropathy Attenuates Proteinuria

Injury to podocytes is a principle cause of initiation and progression of both immune and non-immune mediated glomerular diseases that result in proteinuria and decreased function of the kidney. Current advances in regenerative medicine shed light on the therapeutic potential of cell-based strategies for treatment of such disorders. Thus, there is hope that generation and transplantation of podocytes from induced pluripotent stem cells (iPSCs), could potentially be used as a curative treatment for glomerulonephritis caused by podocytes injury and loss. Despite several reports on the generation of iPSC-derived podocytes, there are rare reports about successful use of these cells in animal models. In this study, we first generated a model of anti-podocyte antibody-induced heavy proteinuria that resembled human membranous nephropathy and was characterized by the presence of sub-epithelial immune deposits and podocytes loss. Thereafter, we showed that transplantation of functional iPSC-derived podocytes following podocytes depletion results in recruitment of iPSC-derived podocytes within the damaged glomerulus, and leads to attenuation of proteinuria and histological alterations. These results provided evidence that application of iPSCs-derived renal cells could be a possible therapeutic strategy to favorably influence glomerular diseases outcomes.

Intraportally delivered stem cell spheroids localize in the liver and protect hepatocytes against GalN/LPS-induced fulminant hepatic toxicity

BACKGROUND

Systemic inflammatory response syndrome (SIRS) is common in severe fulminant hepatic failure (FHF) and has a high mortality rate (20-50%) due to irreversible cerebral edema or sepsis. Stem cell-based treatment has emerged as a promising alternative therapeutic strategy to prolong the survival of patients suffering from FHF via the inhibition of SIRS due to their immunomodulatory effects.

METHODS

3D spheroids of adipose-derived mesenchymal stem cells (3D-ADSC) were prepared by the hanging drop method. The efficacy of the 3D-ADSC to rescue FHF was evaluated in a D-galactosamine/lipopolysaccharide (GalN/LPS)-induced mouse model of FHF via intraportal transplantation of the spheroids.

RESULTS

Intraportally delivered 3D-ADSC better engrafted and localized into the damaged livers compared to 2D-cultured adipose-derived mesenchymal stem cells (2D-ADSC). Transplantation of 3D-ADSC rescued 50% of mice from FHF-induced lethality, whereas only 20% of mice survived when 2D-ADSC were transplanted. The improved transplantation outcomes correlated with the enhanced immunomodulatory effect of 3D-ADSC in the liver microenvironment.

CONCLUSION

The study shows that the transplantation of optimized 3D-ADSC can efficiently ameliorate GalN/LPS-induced FHF due to improved viability, resistance to exogenous ROS, and enhanced immunomodulatory effects of 3D-ADSC.

Nanofibrillar cellulose wound dressing supports the growth and characteristics of human mesenchymal stem/stromal cells without cell adhesion coatings

BACKGROUND

In the field of regenerative medicine, delivery of human adipose-derived mesenchymal stem/stromal cells (hASCs) has shown great promise to promote wound healing. However, a hostile environment of the injured tissue has shown considerably to limit the survival rate of the transplanted cells, and thus, to improve the cell survival and retention towards successful cell transplantation, an optimal cell scaffold is required. The objective of this study was to evaluate the potential use of wood-derived nanofibrillar cellulose (NFC) wound dressing as a cell scaffold material for hASCs in order to develop a cell transplantation method free from animal-derived components for wound treatment.

METHODS

Patient-derived hASCs were cultured on NFC wound dressing without cell adhesion coatings. Cell characteristics, including cell viability, morphology, cytoskeletal structure, proliferation potency, and mesenchymal cell and differentiation marker expression, were analyzed using cell viability assays, electron microscopy, immunocytochemistry, and quantitative or reverse transcriptase PCR. Student's t test and one-way ANOVA followed by a Tukey honestly significant difference post hoc test were used to determine statistical significance.

RESULTS

hASCs were able to adhere to NFC dressing and maintained high cell survival without cell adhesion coatings with a cell density-dependent manner for the studied period of 2 weeks. In addition, NFC dressing did not induce any remarkable cytotoxicity towards hASCs or alter the morphology, proliferation potency, filamentous actin structure, the expression of mesenchymal vimentin and extracellular matrix (ECM) proteins collagen I and fibronectin, or the undifferentiated state of hASCs.

CONCLUSIONS

As a result, NFC wound dressing offers a functional cell culture platform for hASCs to be used further for in vivo wound healing studies in the future.

Potential Novel Strategies for the Treatment of Dental Pulp-Derived Pain: Pharmacological Approaches and Beyond

The diagnosis and management of pain is an everyday occurrence in dentistry, and its effective control is essential to ensure the wellbeing of patients. Most tooth-associated pain originates from the dental pulp, a highly vascularized and innervated tissue, which is encased within mineralized dentin. It plays a crucial role in the sensing of stimuli from the local environment, such as infections (i.e. dental caries) and traumatic injury, leading to a local inflammatory response and subsequently to an increase in intra-pulp pressure, activating nerve endings. However, thermal, chemical, and mechanical stimuli also have the ability to generate dental pulp pain, which presents mechanisms highly specific to this tissue and which have to be considered in pain management. Traditionally, the management of dental pulp pain has mostly been pharmacological, using non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, or restorative (i.e. removal of dental caries), or a combination of both. Both research areas continuously present novel and creative approaches. This includes the modulation of thermo-sensitive transient receptor potential cation channels (TRP) by newly designed drugs in pharmacological research, as well as the use of novel biomaterials, stem cells, exosomes and physical stimulation to obtain pulp regeneration in regenerative medicine. Therefore, the aim of this review is to present an up-to-date account of causes underlying dental pain, novel treatments involving the control of pain and inflammation and the induction of pulp regeneration, as well as insights in pain in dentistry from the physiological, pharmacological, regenerative and clinical perspectives.