Optimising human mesenchymal stem cell numbers for clinical application: a literature review

Head-to-head comparison of relevant cell sources of small extracellular vesicles for cardiac repair: Superiority of embryonic stem cells

Small extracellular vesicles (sEV) derived from various cell sources have been demonstrated to enhance cardiac function in preclinical models of myocardial infarction (MI). The aim of this study was to compare different sources of sEV for cardiac repair and determine the most effective one, which nowadays remains limited. We comprehensively assessed the efficacy of sEV obtained from human primary bone marrow mesenchymal stromal cells (BM-MSC), human immortalized MSC (hTERT-MSC), human embryonic stem cells (ESC), ESC-derived cardiac progenitor cells (CPC), human ESC-derived cardiomyocytes (CM), and human primary ventricular cardiac fibroblasts (VCF), in in vitro models of cardiac repair. ESC-derived sEV (ESC-sEV) exhibited the best pro-angiogenic and anti-fibrotic effects in vitro. Then, we evaluated the functionality of the sEV with the most promising performances in vitro, in a murine model of MI-reperfusion injury (IRI) and analysed their RNA and protein compositions. In vivo, ESC-sEV provided the most favourable outcome after MI by reducing adverse cardiac remodelling through down-regulating fibrosis and increasing angiogenesis. Furthermore, transcriptomic, and proteomic characterizations of sEV derived from hTERT-MSC, ESC, and CPC revealed factors in ESC-sEV that potentially drove the observed functions. In conclusion, ESC-sEV holds great promise as a cell-free treatment for promoting cardiac repair following MI.

Characterization of Rabbit Mesenchymal Stem/Stromal Cells after Cryopreservation

Adipose tissues (ADPs) are an alternative source for mesenchymal stem/stromal cells (MSCs), given that conventional bone marrow (BM) collection is painful and yields limited cell numbers. As the need for easily accessible MSCs grows, cryopreservation's role in regenerative medicine is becoming increasingly vital. However, limited research exists on the characteristics and functional properties of rabbit-derived MSCs from various anatomical sources before and after cryopreservation. We examined the effects of cryopreservation using Bambanker. We found that cryopreservation did not adversely affect the morphology, viability, and adipogenic or chondrogenic differentiation abilities of ADP MSCs or BM MSCs. However, there was a notable drop in the proliferation rate and osteogenic differentiation capability of BM MSCs post-cryopreservation. Additionally, after cryopreservation, the surface marker gene expression of CD90 was not evident in ADP MSCs. As for markers, ADIPOQ can serve as an adipogenic marker for ADP MSCs. ACAN and CNMD can act as chondrogenic markers, but these two markers are not as effective post-cryopreservation on ADP MSCs, and osteogenic markers could not be validated. The study highlights that compared to BM MSCs, ADP MSCs retained a higher viability, proliferation rate, and differentiation potential after cryopreservation. As such, in clinical MSC use, we must consider changes in post-cryopreservation cell functions.

The stereological, immunohistological, and gene expression studies in an infected ischemic wound in diabetic rats treated by human adipose-derived stem cells and photobiomodulation

We investigated the impacts of photobiomodulation (PBM) and human allogeneic adipose-derived stem cells (ha-ADS) together and or alone applications on the stereological parameters, immunohistochemical characterizing of M1 and M2 macrophages, and mRNA levels of hypoxia-inducible factor (HIF-1α), basic fibroblast growth factor (bFGF), vascular endothelial growth factor-A (VEGF-A) and stromal cell-derived factor-1α (SDF-1α) on inflammation (day 4) and proliferation phases (day 8) of repairing tissues in an infected delayed healing and ischemic wound model (IDHIWM) in type 1 diabetic (DM1) rats. DM1 was created in 48 rats and an IDHIWM was made in all of them, and they were distributed into 4 groups. Group1 = control rats with no treatment. Group2 = rats received (10 × 100000 ha-ADS). Group3 = rats exposed to PBM (890 nm, 80 Hz, 3.46 J/cm2). Group4 = rats received both PBM and ha-ADS. On day 8, there were significantly higher neutrophils in the control group than in other groups (p < 0.01). There were substantially higher macrophages in the PBM + ha-ADS group than in other groups on days 4 and 8 (p < 0.001). Granulation tissue volume, on both days 4 and 8, was meaningfully greater in all treatment groups than in the control group (all, p = 0.000). Results of M1 and M2 macrophage counts of repairing tissue in the entire treatment groups were considered preferable to those in the control group (p < 0.05). Regarding stereological and macrophage phenotyping, the results of the PBM + ha-ADS group were better than the ha-ADS and PBM groups. Results of the tested gene expression of repairing tissue on inflammation and proliferation steps in PBM and PBM + ha-ADS groups were meaningfully better than the control and ha-ADS groups (p < 0.05). We showed that PBM, ha-ADS, and PBM plus ha-ADS, hastened the proliferation step of healing in an IDHIWM in rats with DM1 by regulation of the inflammatory reaction, macrophage phenotyping, and augmented granulation tissue formation. In addition PBM and PBM plus ha-ADS protocols hastened and increased mRNA levels of HIF-1α, bFGF, SDF-1α, and VEGF-A. Totally, in terms of stereological and immuno-histological tests, and also gene expression HIF-1α and VEGF-A, the results of PBM + ha-ADS were superior (additive) to PBM, and ha-ADS alone treatments.

Salmonella enhances osteogenic differentiation in adipose-derived mesenchymal stem cells

The potential of mesenchymal stem cells (MSCs) for tissue repair and regeneration has garnered great attention. While MSCs are likely to interact with microbes at sites of tissue damage and inflammation, like in the gastrointestinal system, the consequences of pathogenic association on MSC activities have yet to be elucidated. This study investigated the effects of pathogenic interaction on MSC trilineage differentiation paths and mechanisms using model intracellular pathogen Salmonella enterica ssp enterica serotype Typhimurium. The examination of key markers of differentiation, apoptosis, and immunomodulation demonstrated that Salmonella altered osteogenic and chondrogenic differentiation pathways in human and goat adipose-derived MSCs. Anti-apoptotic and pro-proliferative responses were also significantly upregulated (p &lt; 0.05) in MSCs during Salmonella challenge. These results together indicate that Salmonella, and potentially other pathogenic bacteria, can induce pathways that influence both apoptotic response and functional differentiation trajectories in MSCs, highlighting that microbes have a potentially significant role as influencers of MSC physiology and immune activity.

Prx1+ MPCs Accumulate in the Dura Mater of Wild-Type and p21-/- Mice Followed by a Specific Reduction in p21-/- Dural MPCs

Epidural fat contains a population of mesenchymal progenitor cells (MPCs), and this study explores the behavior of these cells on the adjacent dura mater during growth and in response to injury in a p21 knockout mouse model. p21^-/- mice are known to have increased cell proliferation and enhanced tissue regeneration post-injury. Therefore, it is hypothesized that the process by which epidural fat MPCs maintain the dura mater can be accelerated in p21^-/- mice. Using a Prx1 lineage tracing mouse model, the epidural fat MPCs are found to increase in the dura mater over time in both C57BL/6 (p21^+/+ ) and p21^-/- mice; however, by 3 weeks post-tamoxifen induction, few MPCs are observed in p21^-/- mice. These endogenous MPCs also localize to dural injuries in both mouse strains, with MPCs in p21^-/- mice demonstrating increased proliferation. When epidural fat MPCs derived from p21^-/- mice are transplanted into dural injuries in C57BL/6 mice, these MPCs are found in the injury site. It is demonstrated that epidural fat MPCs play a role in dural tissue maintenance and are able to directly contribute to dural injury repair. This suggests that these MPCs have the potential to treat injuries and/or pathologies in tissues surrounding the spinal cord.

Optimizing human endometrial mesenchymal stem cells for maximal induction of angiogenesis

Human endometrial mesenchymal stem cells (hEMSCs) have been shown to promote neo-vascularization; however, its angiogenic function lessens with age. To determine the optimal conditions for maximizing hEMSC angiogenic capacity, we examined the effects of serial passaging on hEMSC activity. hEMSCs were cultured from passages (P) 3, 6, 9, and 12, and analyzed for proliferation, migration, differentiation and senescence, as well as their capacity to induce angiogenesis. The results showed that hEMSC proliferation and migration significantly decreased after P12. Furthermore, hEMSC differentiation into adipogenic and osteogenic lineages, as well as their proangiogenic capacity, gradually decreased from P9-12, while senescence only occurred after P12. Evaluation of angiogenic-related protein levels showed that both transforming growth factor β2 and Tie-2 was significantly reduced in hEMSCs at P12, compared to P3, possibly serving as the basis behind their lowered angiogenic capacity. Furthermore, in vivo angiogenesis evaluation with Matrigel plug assay showed that the optimal hEMSC to HUVEC ratio, for maximizing vessel formation, was 1:4. This study showed that hEMSC passaging was associated with lowered cellular functioning, bringing them closer to a senescent phenotype, especially after P12, thereby defining the optimal time period for cultivating fully functional hEMSCs for therapeutic applications.

NIR irradiation of human buccal fat pad adipose stem cells and its effect on TRP ion channels

The effect of near infrared (NIR) laser irradiation on proliferation and osteogenic differentiation of buccal fat pad-derived stem cells and the role of transient receptor potential (TRP) channels was investigated in the current research. After stem cell isolation, a 940 nm laser with 0.1 W, 3 J/cm² was used in pulsed and continuous mode for irradiation in 3 sessions once every 48 h. The cells were cultured in the following groups: non-osteogenic differentiation medium/primary medium (PM) and osteogenic medium (OM) groups with laser-irradiated (L +), without irradiation (L -), laser treated + Capsazepine inhibitor (L + Cap), and laser treated + Skf96365 inhibitor (L + Skf). Alizarin Red staining and RT-PCR were used to assess osteogenic differentiation and evaluate RUNX2, Osterix, and ALP gene expression levels. The pulsed setting showed the best viability results (P < 0.05) and was used for osteogenic differentiation evaluations. The results of Alizarin red staining were not statistically different between the four groups. Osterix and ALP expression increased in the (L +) group. This upregulation abrogated in the presence of Capsazepine, TRPV1 inhibitor (L + Cap); however, no significant effect was observed with Skf96365 (L + Skf).

Minimum criteria for defining induced mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a promising cell type for cell-based therapies. The therapeutic potential of MSCs has been verified in preclinical and clinical studies, however; low cell number in adult tissues, restricted expansion and differentiation capacity, and donor-related heterogeneity limit their use. To address these issues, there has been considerable interest in induced pluripotent stem cells (iPSCs) derived MSCs (induced mesenchymal stem cells [iMSCs]). Investigators obtain iMSCs from iPSCs of different origins, with variable methods of generation and expansion. Results of current studies have suggested iMSCs as a unique alternative source of MSCs. However, iMSCs are defined using the same criteria (proposed previously for primary MSCs by the International Society for Cellular Therapy [ISCT]) without realizing the distinct nature of iMSCs as compared to primary MSCs. To rationally define iMSCs, additional characterization is proposed along with ISCT's minimum criteria for defining primary MSCs. Minimum criteria for defining iMSCs should include (1) spindle-shaped morphology, (2) plastic adherent growth, (3) positive expression of CD29, CD44, CD73, CD90, CD105, along with negative expression of hematopoietic markers (CD45, CD34, CD14 or CD11b, CD79α or CD19, HLA-DR), (4) lack of expression of iPSCs induction factors, (5) trilineage differentiation potential, (6) lack of ability to form teratoma, and (7) release of MSC relevant paracrine factors. Defining the minimum criteria for iMSCs will be of great interest in the field and will provide a uniform description and identification of iMSCs to expedite progress in the field. Furthermore, due to increased interest in the clinical use of iMSCs, the above-mentioned additional characterization before the clinical application is important to avoid unwanted complications for recipients.

Yields of mesenchymal stromal cells from synovial fluid reflect those from synovium in patients with rheumatoid arthritis

The yield of primary synovial mesenchymal stromal cells (MSCs) from synovium of patients with rheumatoid arthritis (RA) is highly variable, but cell transplantation therapy with autologous synovial MSCs requires accurate prediction of the synovial MSC yield per synovium weight. Here, we determined whether the yield of synovial fluid MSCs might predict the ultimate yield of primary MSCs from the synovium of RA knees. Synovial fluid and synovium were harvested during total knee arthroplasty from the knee joints of 10 patients with RA. Synovial fluid (1.5 mL) was diluted fourfold and plated equally into six 60 cm² dishes. Nucleated cells from digested synovium were similarly plated at 1 × 10⁴ cells in 6 dishes. All dishes were cultured for 14 days and analyzed for MSC yields and properties, including in vitro chondrogenesis. The cultured synovial cell number was correlated with the cultured synovial fluid cell number (n = 10, R² = 0.64, p < 0.01). Synovial fluid cells formed cell colonies and showed MSC-like surface epitopes and multi-differentiation potential. However, the cartilage pellet weight indicated a greater chondrogenic potential of the synovial MSCs (n = 8). The primary MSC yields from synovial fluid and synovium were correlated, indicating that the synovial fluid MSC yield can predict the ultimate synovial MSC yield.

Comparison of the Effect of MFAT and MFAT + PRP on Treatment of Hip Osteoarthritis: An Observational, Intention-to-Treat Study at One Year

Hip osteoarthritis (OA) is a major contributor to reduced quality of life and concomitant disability associated with lost working life months. Intra-articular injection of various biological materials has shown promise in alleviating symptoms and potentially slowing down the degenerative process. Here, we compared the effects of treatment of a cohort of 147 patients suffering from grade 1–4 hip OA; with either micro-fragmented adipose tissue (MFAT), or a combination of MFAT with platelet-rich plasma (PRP). We found significant improvements in both the visual analogue score for pain (VAS) and Oxford hip score (OHS) that were similar for both treatments with over 60% having an improvement in the VAS score of 20 points or more. These results suggest a positive role for intra-articular injection of MFAT + PRP as a treatment for hip osteoarthritis which may be important particularly in low body mass index (BMI) patients where the difficulty in obtaining sufficient MFAT for treatment could be offset by using this combination of biologicals.

Influence of age on stem cells depends on the sex of the bone marrow donor

Ageing is often accompanied by an increase in bone marrow fat together with reduced bone volume and diseases of the bone such as osteoporosis. As mesenchymal stem cells (MSCs) are capable of forming bone, cartilage and fat tissue, studying these cells is of great importance to understand the underlying mechanisms behind age‐related bone diseases. However, inter‐donor variation has been found when handling MSCs. Therefore, the aim of this study was to investigate the effects of donor age and sex by comparing in vitro characteristics of human bone marrow‐derived MSCs (hBMSCs) from a large donor cohort (n = 175). For this, hBMSCs were analysed for CFU‐F capacity, proliferation, differentiation capacity and surface antigen expression under standardized culture conditions. The results demonstrated a significantly reduced CFU‐F number for hBMSCs of female compared to male donors. Furthermore, there was a significant decrease in the proliferation rate, adipogenic differentiation potential and cell surface expression of SSEA‐4, CD146 and CD274 of hBMSCs with an increase in donor age. Interestingly, all these findings were exclusive to hBMSCs from female donors. Further research should focus on postmenopausal‐related effects on hBMSCs, as the results imply a functional loss and immunophenotypic change of hBMSCs particularly in aged women.

Electromagnetic field exposure as a plausible approach to enhance the proliferation and differentiation of mesenchymal stem cells in clinically relevant scenarios

Mesenchymal stem/stromal cell (MSC)‍-based therapy has been regarded as one of the most revolutionary breakthroughs in the history of modern medicine owing to its myriad of immunoregulatory and regenerative properties. With the rapid progress in the fields of osteo- and musculoskeletal therapies, the demand for MSC-based treatment modalities is becoming increasingly prominent. In this endeavor, researchers around the world have devised new and innovative techniques to support the proliferation of MSCs while minimizing the loss of hallmark features of stem cells. One such example is electromagnetic field (EMF) exposure, which is an alternative approach with promising potential. In this review, we present a critical discourse on the efficiency, practicability, and limitations of some of the relevant methods, with insurmountable evidence backing the implementation of EMF as a feasible strategy for the clinically relevant expansion of MSCs.

Phenotypic and Functional Responses of Human Decidua Basalis Mesenchymal Stem/Stromal Cells to Lipopolysaccharide of Gram-Negative Bacteria

Introduction

Human decidua basalis mesenchymal stem cells (DBMSCs) are potential therapeutics for the medication to cure inflammatory diseases, like atherosclerosis. The current study investigates the capacity of DBMSCs to stay alive and function in a harmful inflammatory environment induced by high levels of lipopolysaccharide (LPS).

Methods

DBMSCs were exposed to different levels of LPS, and their viability and functional responses (proliferation, adhesion, and migration) were examined. Furthermore, DBMSCs’ expression of 84 genes associated with their functional activities in the presence of LPS was investigated.

Results

Results indicated that LPS had no significant effect on DBMSCs’ adhesion, migration, and proliferation (24 h and 72 h) (p > 0.05). However, DBMSCs’ proliferation was significantly reduced at 10 µg/mL of LPS at 48 h (p < 0.05). In addition, inflammatory cytokines and receptors related to adhesion, proliferation, migration, and differentiation were significantly overexpressed when DBMSCs were treated with 10 µg/mL of LPS (p < 0.05).

Conclusion

These results indicated that DBMSCs maintained their functional activities (proliferation, adhesion, and migration) in the presence of LPS as there was no variation between the treated DBMSCs and the control group. This study will lay the foundation for future preclinical and clinical studies to confirm the appropriateness of DBMSCs as a potential medication to cure inflammatory diseases, like atherosclerosis.

Cell-free fat extract accelerates diabetic wound healing in db/db mice

Cell-free fat extract (CEFFE), the liquid fraction derived from fat tissues, is enriched with a variety of growth factors and possesses pro-angiogenic, anti-apoptotic, and anti-oxidative properties. The aim of this study was to determine if CEFFE could accelerate chronic wound healing in mice with diabetes and investigate its underlying mechanisms. A model of circular full-thickness wound (6 mm diameter) was produced in the central dorsal region of spontaneous type 2 diabetes mellitus db/db mice. The mice were divided to three groups depending on dosage of CEFFE administered for the study; high dose CEFFE group (CEFFE^high; administered 2.5 ml/kg/day via subcutaneous injection for six days), low dose CEFFE group (CEFFE^low; administered 2.5 ml/kg/day via subcutaneous injection for three days), and a control group receiving phosphate buffer solution. Wound closure was evaluated on day 3, 7, 10, and 14 post-operation. Histological analyses, including hematoxylin-eosin staining and Masson's trichrome staining and immunohistological staining of anti-CD31 and anti-CD68, were also performed. Moreover, the effects of CEFFE on proliferation, migration, and tube formation of human immortal keratinocyte cells (HaCaT) and human vascular endothelial cells (HUVEC) were tested in vitro. The results showed that the local injection of CEFFE significantly accelerated wound healing in mice with diabetes. CEFFE improved re-epithelization and collagen secretion, promoted angiogenesis, and inhibited inflammatory macrophage infiltration in vivo. CEFFE also promoted HaCaT proliferation and migration and enhanced tubular formation in cultured HUVEC. It was concluded that CEFFE accelerates wound healing through pro-angiogenic and anti-inflammatory activities.

Mesenchymal Stem/Progenitor Cells: The Prospect of Human Clinical Translation

Mesenchymal stem/progenitor cells (MSCs) are key players in regenerative medicine, relying principally on their differentiation/regeneration potential, immunomodulatory properties, paracrine effects, and potent homing ability with minimal if any ethical concerns. Even though multiple preclinical and clinical studies have demonstrated remarkable properties for MSCs, the clinical applicability of MSC-based therapies is still questionable. Several challenges exist that critically hinder a successful clinical translation of MSC-based therapies, including but not limited to heterogeneity of their populations, variability in their quality and quantity, donor-related factors, discrepancies in protocols for isolation, in vitro expansion and premodification, and variability in methods of cell delivery, dosing, and cell homing. Alterations of MSC viability, proliferation, properties, and/or function are also affected by various drugs and chemicals. Moreover, significant safety concerns exist due to possible teratogenic/neoplastic potential and transmission of infectious diseases. Through the current review, we aim to highlight the major challenges facing MSCs' human clinical translation and shed light on the undergoing strategies to overcome them.

Effects of cryopreservation and long-term culture on biological characteristics and proteomic profiles of human umbilical cord-derived mesenchymal stem cells

Background

Human umbilical cord-derived MSCs (hUC-MSCs) have been identified as promising seeding cells in tissue engineering and clinical applications of regenerative medicine due to their advantages of simple acquisition procedure and the capability to come from a young tissue donor over the other MSCs sources. In clinical applications, large scale production is required and optimal cryopreservation and culture conditions are essential to autologous and allogeneic transplantation in the future. However, the influence of cryopreserved post-thaw and long-term culture on hUC-MSCs remains unknown, especially in terms of specific protein expression. Therefore, biological characteristics and proteomic profiles of hUC-MSCs after cryopreserving and long-term culturing were investigated.

Methods

Firstly, hUC-MSCs were isolated from human umbilical cord tissues and identified through morphology, surface markers and tri-lineage differentiation potential at passage 3, and then the biological characteristics and proteomic profiles were detected and compared after cryopreserving and long-term culturing at passage 4 and continuously cultured to passage 10 with detection occurring here as well. The proteomic profiles were tested by using the isobaric tags for relative and absolute quantification (iTRAQ) labeling technique and differential protein were confirmed by mass spectrometry.

Results

The results showed no significant differences in phenotypes including morphology, surface marker and tri-lineage differentiation potential but have obvious changes in translation level, which is involved in metabolism, cell cycle and other pathways.

Conclusion

This suggests that protein expression may be used as an indicator of hUC-MSCs security testing before applying in clinical settings, and it is also expected to provide the foundation or standardization guide of hUC-MSCs applications in regenerative medicine.

Predicting in vitro human mesenchymal stromal cell expansion based on individual donor characteristics using machine learning

BACKGROUND

Human mesenchymal stromal cells (hMSCs) have become attractive candidates for advanced medical cell-based therapies. An in vitro expansion step is routinely used to reach the required clinical quantities. However, this is influenced by many variables including donor characteristics, such as age and gender, and culture conditions, such as cell seeding density and available culture surface area. Computational modeling in general and machine learning in particular could play a significant role in deciphering the relationship between the individual donor characteristics and their growth dynamics.

METHODS

In this study, hMSCs obtained from 174 male and female donors, between 3 and 64 years of age with passage numbers ranging from 2 to 27, were studied. We applied a Random Forests (RF) technique to model the cell expansion procedure by predicting the population doubling time (PDT) for each passage, taking into account individual donor-related characteristics.

RESULTS

Using the RF model, the mean absolute error between model predictions and experimental results for the PDT in passage 1 to 4 is significantly lower compared with the errors obtained with theoretical estimates or historical data. Moreover, statistical analysis indicate that the PD and PDT in different age categories are significantly different, especially in the youngest group (younger than 10 years of age) compared with the other age groups.

DISCUSSION

In summary, we introduce a predictive computational model describing in vitro cell expansion dynamics based on individual donor characteristics, an approach that could greatly assist toward automation of a cell expansion culture process.

Colony Formation, Migratory, and Differentiation Characteristics of Multipotential Stromal Cells (MSCs) from "Clinically Accessible" Human Periosteum Compared to Donor-Matched Bone Marrow MSCs

Periosteum is vital for fracture healing, as a highly vascular and multipotential stromal cell- (MSC-) rich tissue. During surgical bone reconstruction, small fragments of periosteum can be “clinically accessible,” yet periosteum is currently not ultilised, unlike autologous bone marrow (BM) aspirate. This study is aimed at comparing human periosteum and donor-matched iliac crest BM MSC content and characterising MSCs in terms of colony formation, growth kinetics, phenotype, cell migration patterns, and trilineage differentiation capacity. “Clinically accessible” periosteum had an intact outer fibrous layer, containing CD271+ candidate MSCs located perivasculary; the inner cambium was rarely present. Following enzymatic release of cells, periosteum formed significantly smaller fibroblastic colonies compared to BM (6.1 mm² vs. 15.5 mm², n = 4, P = 0.0006). Periosteal colonies were more homogenous in size (range 2-30 mm² vs. 2-54 mm²) and on average 2500-fold more frequent (2.0% vs. 0.0008%, n = 10, P = 0.004) relative to total viable cells. When expanded in vitro, similar growth rates up to passage 0 (P0) were seen (1.8 population doublings (PDs) per day (periosteum), 1.6 PDs per day (BM)); however, subsequently BM MSCs proliferated significantly slower by P4 (4.3 PDs per day (periosteum) vs. 9.3 PDs per day (BM), n = 9, P = 0.02). In early culture, periosteum cells were less migratory at slower speeds than BM cells. Both MSC types exhibited MSC phenotype and trilineage differentiation capacity; however, periosteum MSCs showed significantly lower (2.7-fold) adipogenic potential based on Nile red : DAPI ratios with reduced expression of adipogenesis-related transcripts PPAR-γ. Altogether, these data revealed that “clinically accessible” periosteal samples represent a consistently rich source of highly proliferative MSCs compared to donor-matched BM, which importantly show similar osteochondral capacity and lower adipogenic potential. Live cell tracking allowed determination of unique morphological and migration characteristics of periosteal MSCs that can be used for the development of novel bone graft substitutes to be preferentially repopulated by these cells.

Enhanced Therapeutic Potential of the Secretome Released from Adipose-Derived Stem Cells by PGC-1α-Driven Upregulation of Mitochondrial Proliferation

Peroxisome proliferator activated receptor λ coactivator 1α (PGC-1α) is a potent regulator of mitochondrial biogenesis and energy metabolism. In this study, we investigated the therapeutic potential of the secretome released from the adipose-derived stem cells (ASCs) transfected with PGC-1α (PGC-secretome). We first generated PGC-1α-overexpressing ASCs by transfecting ASCs with the plasmids harboring the gene encoding PGC-1α. Secretory materials released from PGC-1α-overexpressing ASCs were collected and their therapeutic potential was determined using in vitro (thioacetamide (TAA)-treated AML12 cells) and in vivo (70% partial hepatectomized mice) models of liver injury. In the TAA-treated AML12 cells, the PGC-secretome significantly increased cell viability, promoted expression of proliferation-related markers, such as PCNA and p-STAT, and significantly reduced the levels of reactive oxygen species (ROS). In the mice, PGC-secretome injections significantly increased liver tissue expression of proliferation-related markers more than normal secretome injections did (p < 0.05). We demonstrated that the PGC-secretome does not only have higher antioxidant and anti-inflammatory properties, but also has the potential of significantly enhancing liver regeneration in both in vivo and in vitro models of liver injury. Thus, reinforcing the mitochondrial antioxidant potential by transfecting ASCs with PGC-1α could be one of the effective strategies to enhance the therapeutic potential of ASCs.

Platelet-Rich Plasma Improves the Wound Healing Potential of Mesenchymal Stem Cells through Paracrine and Metabolism Alterations

Chronic and acute nonhealing wounds represent a major public health problem, and replacement of cutaneous lesions by the newly regenerated skin is challenging. Mesenchymal stem cells (MSC) and platelet-rich plasma (PRP) were separately tested in the attempt to regenerate the lost skin. However, these treatments often remained inefficient to achieve complete wound healing. Additional studies suggested that PRP could be used in combination with MSC to improve the cell therapy efficacy for tissue repair. However, systematic studies related to the effects of PRP on MSC properties and their ability to rebuild skin barrier are lacking. We evaluated in a mouse exhibiting 4 full-thickness wounds, the skin repair ability of a treatment combining human adipose-derived MSC and human PRP by comparison to treatment with saline solution, PRP alone, or MSC alone. Wound healing in these animals was measured at day 3, day 7, and day 10. In addition, we examined in vitro and in vivo whether PRP alters in MSC their proangiogenic properties, their survival, and their proliferation. We showed that PRP improved the efficacy of engrafted MSC to replace lost skin in mice by accelerating the wound healing processes and ameliorating the elasticity of the newly regenerated skin. In addition, we found that PRP treatment stimulated in vitro, in a dose-dependent manner, the proangiogenic potential of MSC through enhanced secretion of soluble factors like VEGF and SDF-1. Moreover, PRP treatment ameliorated the survival and activated the proliferation of in vitro cultured MSC and that these effects were accompanied by an alteration of the MSC energetic metabolism including oxygen consumption rate and mitochondrial ATP production. Similar observations were found in vivo following combined administration of PRP and MSC into mouse wounds. In conclusion, our study strengthens that the use of PRP in combination with MSC might be a safe alternative to aid wound healing.

Androgens and Androgen Receptor Actions on Bone Health and Disease: From Androgen Deficiency to Androgen Therapy

Androgens are not only essential for bone development but for the maintenance of bone mass. Therefore, conditions with androgen deficiency, such as male hypogonadism, androgen-insensitive syndromes, and prostate cancer with androgen deprivation therapy are strongly associated with bone loss and increased fracture risk. Here we summarize the skeletal effects of androgens—androgen receptors (AR) actions based on in vitro and in vivo studies from animals and humans, and discuss bone loss due to androgens/AR deficiency to clarify the molecular basis for the anabolic action of androgens and AR in bone homeostasis and unravel the functions of androgen/AR signaling in healthy and disease states. Moreover, we provide evidence for the skeletal benefits of androgen therapy and elucidate why androgens are more beneficial than male sexual hormones, highlighting their therapeutic potential as osteoanabolic steroids in improving bone fracture repair. Finally, the application of selective androgen receptor modulators may provide new approaches for the treatment of osteoporosis and fractures as well as building stronger bones in diseases dependent on androgens/AR status.

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.

Donor Variability in Growth Kinetics of Healthy hMSCs Using Manual Processing: Considerations for Manufacture of Cell Therapies

Human mesenchymal stromal cells (hMSCs) are excellent candidates for cell therapy but their expansion to desired clinical quantities can be compromised by ex vivo processing, due to differences between donor material and process variation. The aim of this article is to characterize growth kinetics of healthy baseline "reference" hMSCs using typical manual processing. Bone-marrow derived hMSCs from ten donors are isolated based on plastic adherence, expanded, and analyzed for their growth kinetics until passage 4. Results indicate that hMSC density decreases with overall time in culture (p < 0.001) but no significant differences are observed between successive passages after passage 1. In addition, fold increase in cell number dropped between passage 1 and 2 for three batches, which correlated to lower performance in total fold increase and expansion potential of these batches, suggesting that proliferative ability of hMSCs can be predicted at an early stage. An indicative bounded operating window is determined between passage 1 and 3 (PDL < 10), despite the high inter-donor variability present under standardized hMSC expansion conditions used. hMSC growth profile analysis will be of benefit to cell therapy manufacturing as a tool to predict culture performance and attainment of clinically-relevant yields, therefore stratifying the patient population based on early observation.

Exploiting Heparan Sulfate Proteoglycans in Human Neurogenesis-Controlling Lineage Specification and Fate

Unspecialized, self-renewing stem cells have extraordinary application to regenerative medicine due to their multilineage differentiation potential. Stem cell therapies through replenishing damaged or lost cells in the injured area is an attractive treatment of brain trauma and neurodegenerative neurological disorders. Several stem cell types have neurogenic potential including neural stem cells (NSCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and mesenchymal stem cells (MSCs). Currently, effective use of these cells is limited by our lack of understanding and ability to direct lineage commitment and differentiation of neural lineages. Heparan sulfate proteoglycans (HSPGs) are ubiquitous proteins within the stem cell microenvironment or niche and are found localized on the cell surface and in the extracellular matrix (ECM), where they interact with numerous signaling molecules. The glycosaminoglycan (GAG) chains carried by HSPGs are heterogeneous carbohydrates comprised of repeating disaccharides with specific sulfation patterns that govern ligand interactions to numerous factors including the fibroblast growth factors (FGFs) and wingless-type MMTV integration site family (Wnts). As such, HSPGs are plausible targets for guiding and controlling neural stem cell lineage fate. In this review, we provide an overview of HSPG family members syndecans and glypicans, and perlecan and their role in neurogenesis. We summarize the structural changes and subsequent functional implications of heparan sulfate as cells undergo neural lineage differentiation as well as outline the role of HSPG core protein expression throughout mammalian neural development and their function as cell receptors and co-receptors. Finally, we highlight suitable biomimetic approaches for exploiting the role of HSPGs in mammalian neurogenesis to control and tailor cell differentiation into specific lineages. An improved ability to control stem cell specific neural lineage fate and produce abundant cells of lineage specificity will further advance stem cell therapy for the development of improved repair of neurological disorders. We propose a deeper understanding of HSPG-mediated neurogenesis can potentially provide novel therapeutic targets of neurogenesis.

Mesenchymal-like stem cells in canine ovary show high differentiation potential

OBJECTIVES

Recent studies have reported the existence of stem cells in ovarian tissue that show enhanced proliferative and differentiation potential compared to other adult tissues. Based on this evidence, we hypothesized that ovarian tissue contained mesenchymal-like stem cells (MSC) that could be isolated using a novel rapid plastic adhesion technique.

MATERIALS AND METHODS

We established MSC lines derived from ovarian and adipose tissue based on their ability to rapidly adhere to plastic culture dishes in the first 3 hours after plating and studied their potentiality in terms of molecular markers and differentiation capacity.

RESULTS

Morphological and kinetic properties of in vitro cultured ovarian MSC were similar to adipose-derived MSC, and both reached senescence after similar passage numbers. Ovarian-derived MSC expressed mesenchymal (CD90 and CD44) but not haematopoietic markers (CD34 and CD45), indicating similarity to adipose-derived MSC. Moreover, ovarian-derived MSC expressed NANOG, TERT, SOX2, OCT4 and showed extensive capacity to differentiate not only into adipogenic, osteogenic and chondrogenic tissue but also towards neurogenic and endodermal lineages and even precursors of primordial germ cells.

CONCLUSION

These results show for the first time the derivation of ovarian cells with the molecular properties of MSC as well as wide differentiation potential. Canine ovarian tissue is accessible, expandable, multipotent and has high plasticity, holding promise for applications in regenerative medicine.

Mesenchymal stem cell in venous leg ulcer: An intoxicating therapy

Venous leg ulcers (VLU) are a prevalent and reoccurring type of complicated wound, turning as a considerable public healthcare issue, with critical social and economic concern. There are both medical and surgical therapies to treat venous leg ulcers; however, a cure does not yet exist. Mesenchymal stem cells (MSC) are capable and proved of accelerating wound healing in vivo and their study with human chronic wounds is currently awaited. MSCs are a promising source of adult progenitor cells for cellular therapy and have been demonstrated to differentiate into various mesenchymal cell lineages. They have a crucial and integral role in native wound healing by regulating immune response and inflammation. Improved understanding of the cellular and molecular mechanisms at work in delayed wound healing compels to the development of cellular therapy in VLU. This review focuses on the current treatment option of VLU and further emphasizing the role of MSCs in accelerating the healing process. With further understanding of the mechanism of action of these cells in wound improvement and, the involvement of cytokines can also be revealed that could be used for the therapeutic purpose for VLU healing. Clinical uses of MSCs have been started already, and induced MSCs are surely a promising tool or compelling therapy for VLU.

The Impact of Confluence on Bone Marrow Mesenchymal Stem (BMMSC) Proliferation and Osteogenic Differentiation

Background: In the field of cellular therapy, the impact of confluence degreeonharvesting or differentiation of BMMSCs and the effect of cell-to-cell contact remain controversial. Therefore, the effect of confluence on properties of BMMSCs was studied and efficiency of confluence-associated osteogenic differentiation was identified. Materials andMethods: The impact of 20, 50, 70, 80 and 100% confluences on proliferation properties of BMMSCs, expression of ERK and p-ERK proteins and glucose consumption rate was studied. Efficiency of confluence-associated osteogenic differentiation was identified by determining calcium deposition, Alizarin Red staining, ALP activity and expression of osteopontin and osteocalcin genes. Results: There was a correlation between confluence % and BMMSCs density. Viability was declined at the lower and higher confluences. The highest CFU-F, Brd-U uptake and population doubling were obtained at 80% confluence. ERK band intensity in 100% confluent BMMSCs was lower compared to other confluences. Bands of p-ERK were highly detectable in 70% and 80% confluences. Glucose consumption rate of 70% and 80% confluences in the last days were higher than 20% and 100% confluences. Although higher osteogenic differentiation was estimated at 80% confluence using calcium deposition, Alizarin Red staining and ALP activity, it was also extended at 100% confluence Osteopontin gene was expressed among all confluences including 100% confluence, while osteocalcin gene was expressed highly in 70% confluent cells. Conclusion: We concluded that the optimum seeding density for maximal expansion and harvesting purposes is 80% confluence and for osteogenic differentiation up to 100% confluence is also acceptable.

Down-regulation of 21A Alu RNA as a tool to boost proliferation maintaining the tissue regeneration potential of progenitor cells

21A is an Alu non-coding (nc) RNA transcribed by RNA polymerase (pol) III. While investigating the biological role of 21A ncRNA we documented an inverse correlation between its expression level and the rate of cell proliferation. The downregulation of this ncRNA not only caused a boost in cell proliferation, but was also associated to a transient cell dedifferentiation, suggesting a possible involvement of this RNA in cell dedifferentiation/reprogramming. In this study, we explored the possibility to enhance proliferation and dedifferentiation of cells of interest, by 21A down-regulation, using a mixture of chemically modified Anti-21A RNAs. Our results confirmed the validity of this approach that allows the amplification of specific cell populations, in a controlled manner and without inducing permanent effects. In addition to induce cell proliferation, the procedure did not decrease the tissue regeneration potential of progenitor cells in two different cell systems.

Using Stem Cells to Grow Artificial Tissue for Peripheral Nerve Repair

Peripheral nerve injury continues to pose a clinical hurdle despite its frequency and advances in treatment. Unlike the central nervous system, neurons of the peripheral nervous system have a greater ability to regenerate. However, due to a number of confounding factors, this is often both incomplete and inadequate. The lack of supportive Schwann cells or their inability to maintain a regenerative phenotype is a major factor. Advances in nervous system tissue engineering technology have led to efforts to build Schwann cell scaffolds to overcome this and enhance the regenerative capacity of neurons following injury. Stem cells that can differentiate along a neural lineage represent an essential resource and starting material for this process. In this review, we discuss the different stem cell types that are showing promise for nervous system tissue engineering in the context of peripheral nerve injury. We also discuss some of the biological, practical, ethical, and commercial considerations in using these different stem cells for future clinical application.

Peptide Conjugation to a Polymer Coating via Native Chemical Ligation of Azlactones for Cell Culture

Conjugation of biomolecules for stable presentation is an essential step toward reliable chemically defined platforms for cell culture studies. In this work, we describe the formation of a stable and site-specific amide bond via the coupling of a cysteine terminated peptide at low concentration to an azlactone containing copolymer coating. A copolymer of polyethylene glycol methyl ether methacrylate-ran-vinyl azlactone-ran-glycidyl methacrylate P(PEGMEMA-r-VDM-r-GMA) was used to form a thin coating (20-30 nm) on silicon and polycarbonate substrates. The formation and stability of coating-peptide bonds for peptides containing free thiols and amines were quantified by X-ray photoelectron spectroscopy (XPS) after exposure to cell culture conditions. Peptides containing a thiol as the only nucleophile coupled via a thioester bond; however, the bond was labile under cell culture conditions and almost all the bound peptides were displaced from the surface over a period of 2 days. Coupling with N-terminal primary amine peptides resulted in the formation of an amide bond with low efficiency (<20%). In contrast, peptides containing an N-terminal cysteine, which contain both nucleophiles (free thiol and amine) in close proximity, bound with 67% efficiency under neutral pH, and were stable under the same conditions for 2 weeks. Control studies confirm that the stable amide formation was a result of an intramolecular rearrangement through a N-acyl intermediate that resembles native chemical ligation. Through a combination of XPS and cell culture studies, we show that the cysteine terminated peptides undergo a native chemical ligation process at low peptide concentration in aqueous media, short reaction time, and at room temperature resulting in the stable presentation of peptides beyond 2 weeks for cell culture studies.

Optimal Seeding Densities for In Vitro Chondrogenesis of Two- and Three-Dimensional-Isolated and -Expanded Bone Marrow-Derived Mesenchymal Stromal Stem Cells Within a Porous Collagen Scaffold

Bone marrow-derived mesenchymal stromal stem cells (BMSCs) are a promising cell source for treating articular cartilage defects. The objective of this study was to assess the impact of cell seeding density within a collagen I scaffold on in vitro BMSC chondrogenesis following isolation and expansion in two-dimensional (2D) and three-dimensional (3D) environments. It was hypothesized that both expansion protocols would produce BMSCs capable of hyaline-like chondrogenesis with an optimal seeding density of 10 × 10(6) cells/cm(3). Ovine BMSCs were isolated in a 2D environment by plastic adherence, expanded to passage two in flasks containing an expansion medium, and seeded within collagen I scaffolds at densities of 50, 10, 5, 1, and 0.5 × 10(6) BMSCs/cm(3). For 3D isolation and expansion, aspirates containing known quantities of mononucleated cells (bone marrow-derived mononucleated cells [BMNCs]) were seeded on scaffolds at 50, 10, 5, 1, and 0.5 × 10(6) BMNCs/cm(3) and cultured in the expansion medium for an equivalent duration to 2D expansion. Constructs were differentiated in vitro in the chondrogenic medium for 21 days and assessed with reverse-transcription quantitative polymerase chain reaction, safranin O staining, histological scoring using the Bern Score, collagen immunofluorescence, and glycosaminoglycan (GAG) quantification. Two-dimensional-expanded BMSCs seeded at all densities were capable of proteoglycan production and displayed increased expressions of aggrecan and collagen II messenger RNA (mRNA) relative to predifferentiation controls. Collagen II deposition was apparent in scaffolds seeded at 0.5-10 × 10(6) BMSCs/cm(3). Chondrogenesis of 2D-expanded BMSCs was most pronounced in scaffolds seeded at 5-10 × 10(6) BMSCs/cm(3) based on aggrecan and collagen II mRNA, safranin O staining, Bern Score, total GAG, and GAG/deoxyribonucleic acid (DNA). For 3D-expanded BMSC-seeded scaffolds, increased aggrecan and collagen II mRNA expressions relative to controls were noted with all densities. Proteoglycan deposition was present in scaffolds seeded at 0.5-50 × 10(6) BMNCs/cm(3), while collagen II deposition occurred in scaffolds seeded at 10-50 × 10(6) BMNCs/cm(3). The highest levels of aggrecan and collagen II mRNA, Bern Score, total GAG, and GAG/DNA occurred with seeding at 50 × 10(6) BMNCs/cm(3). Within a collagen I scaffold, 2D- and 3D-expanded BMSCs are capable of hyaline-like chondrogenesis with optimal cell seeding densities of 5-10 × 10(6) BMSCs/cm(3) and 50 × 10(6) BMNCs/cm(3), respectively.

Insurance approval of mesenchymal stem cell for acute GVHD in Japan: need of follow up for some remaining concerns

Acute graft-versus-host disease (aGVHD) is a major obstacle following allogeneic hematopoietic stem cell transplantation. Steroid is the standard treatment for aGVHD grade II-IV; however, nearly half of patients do not respond to the therapy. Many drugs have been proposed, but no standard therapy has been determined. This is because of the resistance to these drugs and of infections due to prolonged immunosuppressive states. Over the past decade a new approach using mesenchymal stem cells (MSCs) has been emerging in Japan and western countries. MSCs have unique characteristics such as specific immunosuppressive properties, no immunogenicity on their own and supportive activity for hematopoiesis. Most of the published trials have reported a favorable effect in acute GVHD, but a phase III trial failed to reach the primary endpoint, although, subgroup analyses found significant effects on gut and liver GVHD in the patients with MSCs infusion. In Japan several institutes are trying to develop MSC for clinical use in post HSCT patients. However, several limitations make it difficult to use MSC in clinical practice. Recently we conducted a phase II/III study using MSC (JR-031) for patients with steroid-refractory grade III or IV aGVHD. From the feasible clinical results, JR-031 was approved by PMDA as the first product which meets the Act to Revise the Pharmaceutical Affairs Act and the Act to Ensure the Safety of Regenerative Medicine. The cost of one series of the treatment is more than ten million yen. Now we encounter new issues such as cost, indication, safety and efficacy. The mechanism of MSC is still unclear and potential concerns about ectopic tissue formation and MSC related malignancy in vivo remain. In conclusion, MSC infusions are well tolerated and show benefit in some patients without adverse safety effects; however, long-term follow-up is needed to be more certain of this.

Neuromuscular Regeneration: Perspective on the Application of Mesenchymal Stem Cells and Their Secretion Products

Mesenchymal stem cells are posing as a promising character in the most recent therapeutic strategies and, since their discovery, extensive knowledge on their features and functions has been gained. In recent years, innovative sources have been disclosed in alternative to the bone marrow, conveying their associated ethical concerns and ease of harvest, such as the umbilical cord tissue and the dental pulp. These are also amenable of cryopreservation and thawing for desired purposes, in benefit of the donor itself or other patients in pressing need. These sources present promising possibilities in becoming useful cell sources for therapeutic applications in the forthcoming years. Effective and potential applications of these cellular-based strategies for the regeneration of peripheral nerve are overviewed, documenting recent advances and identified issues for this research area in the near future. Finally, besides the differentiation capacities attributed to mesenchymal stem cells, advances in the recognition of their effective mode of action in the regenerative theatre have led to a new area of interest: the mesenchymal stem cells' secretome. The paracrine modulatory pathway appears to be a major mechanism by which these are beneficial to nerve regeneration and comprehension on the specific growth factors, cytokine, and extracellular molecules secretion profiles is therefore of great interest.

Effects of Human Umbilical Cord Mesenchymal Stem Cells on Human Trophoblast Cell Functions In Vitro

Trophoblast cell dysfunction is involved in many disorders during pregnancy such as preeclampsia and intrauterine growth restriction. Few treatments exist, however, that target improving trophoblast cell function. Human umbilical cord mesenchymal stem cells (hUCMSCs) are capable of self-renewing, can undergo multilineage differentiation, and have homing abilities; in addition, they have immunomodulatory effects and paracrine properties and thus are a prospective source for cell therapy. To identify whether hUCMSCs can regulate trophoblast cell functions, we treated trophoblast cells with hUCMSC supernatant or cocultured them with hUCMSCs. Both treatments remarkably enhanced the migration and invasion abilities of trophoblast cells and upregulated their proliferation ability. At a certain concentration, hUCMSCs also modulated hCG, PIGF, and sEndoglin levels in the trophoblast culture medium. Thus, hUCMSCs have a positive effect on trophoblast cellular functions, which may provide a new avenue for treatment of placenta-related diseases during pregnancy.

The Proportion of ALDEFLUOR-Positive Cancer Stem Cells Changes with Cell Culture Density Due to the Expression of Different ALDH Isoforms

A significant number of discrepancies exist within the literature regarding ALDEFLUOR-positive stem cell populations in cell lines. We hypothesized that these inconsistencies resulted from differences in culture conditions, particularly cell density. We cultured several colon cancer cell lines (N=8) at high and low densities and found a significant decrease in ALDEFLUOR-positive cell populations at high density. However, we found no changes in the CD166-positive stem cell population, self-renewal, or cell cycle distribution of cells cultured at different densities. Interestingly, when we sorted both ALDEFLUOR positive and negative populations from the different density cultures, we identified a significant number of Aldehyde dehydrogenase (ALDH) isoforms whose expression was decreased in ALDEFLUOR-positive stem cells cultured at high density. This novel finding suggests that multiple ALDH isoforms contribute to ALDEFLUOR activity in colon cancer stem cells and decreases in ALDEFLUOR-positive stem cells at high cell density are due to decreased expression of multiple ALDH isoforms. Thus, designing therapeutics to target ALDEFLUOR-positive cancer stem cells may require inhibition of multiple ALDH isoforms.

Concise review: androgen receptor differential roles in stem/progenitor cells including prostate, embryonic, stromal, and hematopoietic lineages

Stem/progenitor (S/P) cells are special types of cells that have the ability to generate tissues throughout their entire lifetime and play key roles in the developmental process. Androgen and the androgen receptor (AR) signals are the critical determinants in male gender development, suggesting that androgen and AR signals might modulate the behavior of S/P cells. In this review, we summarize the AR effects on the behavior of S/P cells, including self-renewal, proliferation, apoptosis, and differentiation in normal S/P cells, as well as proliferation, invasion, and self-renewal in prostate cancer S/P cells. AR plays a protective role in the oxidative stress-induced apoptosis in embryonic stem cells. AR inhibits the self-renewal of embryonic stem cells, bone marrow stromal cells, and prostate S/P cells, but promotes their differentiation except for adipogenesis. However, AR promotes the proliferation of hematopoietic S/P cells and stimulates hematopoietic lineage differentiation. In prostate cancer S/P cells, AR suppresses their self-renewal, metastasis, and invasion. Together, AR differentially influences the characteristics of normal S/P cells and prostate cancer S/P cells, and targeting AR might improve S/P cell transplantation therapy, especially in embryonic stem cells and bone marrow stromal cells.

Stem cell therapy for cardiac regeneration: hits and misses

Cardiac injury and loss of cardiomyocytes is a causative as well as a resultant condition of cardiovascular disorders, which are the leading cause of death throughout the world. This loss of cardiomyocytes cannot be completely addressed through the currently available drugs being administered, which mainly function only in relieving the symptoms. There is a huge potential being investigated for regenerative and cell replacement therapies through recruiting stem cells of various origins namely embryonic, reprogramming/induction, and adult tissue. These sources are being actively studied for translation to clinical scenarios. In this review, we attempt to discuss some of these promising scenarios, including the clinical trials and the obstacles that need to be overcome, and hope to address the direction in which stem cell therapy is heading.

Bone marrow-derived mesenchymal stem cells for the treatment of heart failure

Heart failure remains a major cause of death and disability, requiring rapid development of new therapies. Bone marrow-derived mesenchymal stem cell (MSC)-based therapy is an emerging approach for the treatment of both acute and chronic heart failure. Following successful experimental studies in a range of models, more than 40 clinical trials of MSC-based therapy for heart failure have now been registered, and the results of completed clinical trials so far have shown feasibility and safety of this approach with therapeutic potential suggested (though preliminarily). However, there appear to be several critical issues to be solved before this treatment could become a widespread standard therapy for heart failure. In this review, we comprehensively and systemically summarize a total of 73 preclinical studies and 11 clinical trial reports published to date. By analyzing the data in these reports, (1) improvement in the cell delivery method to the heart in order to enhance donor cell engraftment, (2) elucidation of mechanisms underpinning the therapeutic effects of the treatment differentiation and/or treatment secretion, and (3) validation of the utility of allogeneic MSCs which could enhance the efficacy and expand the application/indication of this therapeutic approach are highlighted as future perspectives. These important respects are further discussed in this review article with referencing latest scientific and clinical information.

Autoserum: An Optimal Supplement for Bone Marrow Mesenchymal Stem Cells of Liver-Injured Rats

Mesenchymal stem cells (MSCs) are an attractive source for the clinical cell therapy of liver injury. Although the use of adult serum, platelet lysate, or cord blood serum solves some of the problems caused by fetal bovine serum (FBS), the allogeneic immune response, contamination, and donor-to-donor and donor-to-receptor differences still obstruct the application of MSCs. In this study, the influences of autoserum from liver-injured rats (LIRs) and allogeneic serum from healthy rats on the isolation and culture of bone marrow MSCs (BMSCs) were examined and compared to FBS. The results showed that BMSCs cultured with autoserum or allogeneic serum exhibited better MSC-specific morphology, lower rate of cell senescent, and higher proliferation kinetics than those with FBS. In addition, autoserum promoted the osteogenic differentiation potential of BMSCs as allogeneic serum did. Although there were no significant differences in proliferation activity, immunophenotypic characterization, and differentiation potential between BMSCs cultured with autoserum and those with allogeneic serum, the potential adverse immunological reactions in patients with allogeneic material transplantation must be considered. We therefore believe that the autoserum from liver-injured patients may be a better choice for MSC expansion to meet the needs of liver injury therapy.

Therapeutic doses of multipotent stromal cells from minimal adipose tissue

Low yield of adult adipose-derived multipotent stromal cells (ASC) can limit autologous cell therapy in individuals with minimal adipose tissue. In this study, ASC isolation was optimized from approximately 0.2 g of feline epididymal adipose tissue for a treatment dose of 10⁶–10⁷ ASCs/kg. The ASC yield was determined for three digestions, 0.1 % collagenase in medium for 30 min (Classic), 0.3 % collagenase in buffer for 30 min (New) and 0.3 % collagenase in buffer for 1 h (Hour). After isolation by the new tissue digestion, continuously cultured ASCs (fresh) and cells recovered and expanded after cryostorage at P0 (revitalized) were characterized up to cell passage (P) 5. Outcomes included CD9, CD29, CD44, CD90 and CD105 expression, cell doublings and doubling times, fibroblastic, adipogenic and osteogenic colony forming unit (CFU) frequency percentages and lineage-specific target gene expression after induction. The New digestion had the highest CFU yield, and about 7x10⁶ ASCs/kg were available within three cell passages (P2). Compared to earlier passages, target surface antigen expression was lowest in fresh P5 cells, and fresh and revitalized P3–5 cells had slower expansion. Fresh and revitalized P1 ASCs had higher CFU frequency percentages and lineage-specific gene expression than P3. The New method described in this study was most efficient for feline epididymal ASC isolation and did not alter in vitro cell behavior. Fresh and revitalized P0-P2 feline ASCs may be most effective for preclinical and clinical trials. This study offers a potential option for ASC isolation from limited adipose tissue resources across species.

In vitro augmentation of mesenchymal stem cells viability in stressful microenvironments : In vitro augmentation of mesenchymal stem cells viability

Mesenchymal stem cells (MSCs) are under intensive investigation for use in cell-based therapies because their differentiation abilities, immunomodulatory effects, and homing properties offer potential for significantly augmenting regenerative capacity of many tissues. Nevertheless, major impediments to their therapeutic application, such as low proliferation and survival rates remain as obstacles to broad clinical use of MSCs. Another major challenge to evolution of MSC-based therapies is functional degradation of these cells as a result of their exposure to oxidative stressors during isolation. Indeed, oxidative stress-mediated MSC depletion occurs due to inflammatory processes associated with chemotherapy, radiotherapy, and expression of pro-apoptotic factors, and the microenvironment of damaged tissue in patients receiving MSC therapy is typically therapeutic not favorable to their survival. For this reason, any strategies that enhance the viability and proliferative capacity of MSCs associated with their therapeutic use are of great value. Here, recent strategies used by various researchers to improve MSC allograft function are reviewed, with particular focus on in vitro conditioning of MSCs in preparation for clinical application. Preconditioning, genetic manipulation, and optimization of MSC culture conditions are some examples of the methodologies described in the present article, along with novel strategies such as treatment of MSCs with secretome and MSC-derived microvesicles. This topic material is likely to find value as a guide for both research and clinical use of MSC allografts and for improvement of the value that use of these cells brings to health care.

Substance P enhances the proliferation and migration potential of murine bone marrow-derived mesenchymal stem cell-like cell lines

Due to the therapeutic characteristics of bone marrow (BM)-derived mesenchymal stem cells (MSCs), clinical trials are testing the use of autologous or allogeneic MSCs for the treatment of several conditions. These therapies require large numbers of MSCs and numerous studies are attempting to find substances that could enhance the egression of endogenous MSCs from the BM into the periphery and increase their proliferation in vivo and in vitro. It has been reported that substance P (SP) has the potential to increase the expansion of MSCs in vivo and to induce their mobilization from the BM into the periphery. The aim of the present study was to investigate the effects of SP on the migration and proliferation potential of two BM-derived MSC-like cell lines, ST2 and OP9. SP was found to induce the migration potential of ST2 cells in vitro. Furthermore, SP increased the proliferation of the MSCs cell line, OP9 cell line. Cyclin D1 expression was observed to increase in the OP9 cells, indicating the activation of the cell cycle in response to SP. The upstream signals involved in these phenomena have yet to be elucidated, although previous studies have proposed the activation of the extracellular signal-regulated kinase-1/2 and Wingless/β-catenin pathways as possible mediators of the cellular proliferation of human MSCs in response to SP. The present results therefore suggest that SP would facilitate the obtainment of higher numbers of endogenous MSCs from patients or donors and/or shorten the process of in vitro expansion that could cause the MSCs to undergo changes in their innate therapeutic characteristics prior to their use in therapy.

Fluorescence based cell counting in collagen monolayer cultures of primary hepatocytes

Accurate determination of cell number is essential for the quantitative description of biological processes. The changes should be related to a measurable reference e.g. in the case of cell culture, the viable cell number is a very valuable reference parameter. Indirect methods of cell number/viability measurements may have up to 10 % standard deviation. This can lead to undesirable large deviations in the analysis of "-omics" data as well as time course studies. Such data should be preferably normalized to the exact viable cell number at a given time to allow meaningful interpretation and understanding of the biological processes. Manual counting of cell number is very laborious and not possible in certain experimental setups. We therefore, developed a simple and reliable fluorescence based method with an accuracy of 95-98 % for the determination of the viable cell number in situ. We optimized the seeding cell densities for primary rat hepatocytes for optimal cell adhesion. This will help in efficient use of primary cells which are usually limited in availability. The method will be very useful in the application of "-omics" techniques, especially metabolome analysis where the specific rates of uptake/production of metabolites can be reliably calculated.