An optimized growth factor cocktail for ovine mesenchymal stem cells

The Research Progress of Mitochondrial Transplantation in the Treatment of Mitochondrial Defective Diseases

Mitochondria are double-membrane organelles that are involved in energy production, apoptosis, and signaling in eukaryotic cells. Several studies conducted over the past decades have correlated mitochondrial dysfunction with various diseases, including cerebral ischemia, myocardial ischemia-reperfusion, and cancer. Mitochondrial transplantation entails importing intact mitochondria from healthy tissues into diseased tissues with damaged mitochondria to rescue the injured cells. In this review, the different mitochondrial transplantation techniques and their clinical applications have been discussed. In addition, the challenges and future directions pertaining to mitochondrial transplantation and its potential in the treatment of diseases with defective mitochondria have been summarized.

Research Progress on Cardiac Tissue Construction of Mesenchymal Stem Cells for Myocardial Infarction

Heart failure is still the main complication affecting the prognosis of acute myocardial infarction (AMI), and mesenchymal stem cells (MSCs) are an effective treatment to replace necrotic myocardium and improve cardiac functioning. However, the transplant survival rate of MSCs still presents challenges. In this review, the biological characteristics of MSCs, the progress of mechanism research in the treatment of myocardial infarction, and the advances in improving the transplant survival rate of MSCs in the replacement of necrotic myocardial infarction are systematically described. From a basic to advanced clinical research, MSC transplants have evolved from a pure injection, an exosome injection, the genetic modification of MSCs prior to injection to the cardiac tissue engineering of MSC patch grafting. This study shows that MSCs have wide clinical applications in the treatment of AMI, suggesting improved myocardial tissue creation. A broader clinical application prospect will be explored and developed to improve the survival rate of MSC transplants and myocardial vascularization.

Biodegradable Microparticles for Regenerative Medicine: A State of the Art and Trends to Clinical Application

Tissue engineering and cell therapy are very attractive in terms of potential applications but remain quite challenging regarding the clinical aspects. Amongst the different strategies proposed to facilitate their implementation in clinical practices, biodegradable microparticles have shown promising outcomes with several advantages and potentialities. This critical review aims to establish a survey of the most relevant materials and processing techniques to prepare these micro vehicles. Special attention will be paid to their main potential applications, considering the regulatory constraints and the relative easiness to implement their production at an industrial level to better evaluate their application in clinical practices.

Differential Development of Umbilical Cord-Derived Mesenchymal Stem Cells During Long-Term Maintenance in Fetal Bovine Serum-Supplemented Medium and Xeno- and Serum-Free Culture Medium

Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) are believed to have potential for the treatment of various diseases; thus, many scientists have investigated the molecular mechanisms underlying the function of UC-MSCs and, for example, the appropriate media for large-scale UC-MSC expansion to prepare cells for real-world application. In this study, we investigated the cellular morphology, proliferation capacity, surface markers, cellular senescence signals, clonogenic potential, trilineage differentiation capacity, and secreted factors of human primary UC-MSCs in long-term culture from passage 2 (P2) to passage 10 (P10) with either conventional fetal bovine serum (FBS)-supplemented medium or commercial xeno- and serum-free medium (StemMACS™). We found that the cells cultured in both media had similar morphology and marker expression. However, the proliferation kinetics as measured by the cell population doubling time differed in a passage (P2-P10)-dependent manner between the cells cultured in the two media; sustainable growth was observed in cells maintained in xeno- and serum-free medium. Moreover, significant differences in cellular senescence signals were observed, with more aging cells in the cell population cultured in FBS-containing medium. Colony numbers and the day that the first colony appeared were similar; however, UC-MSC colony sizes were smaller when cultured in FBS-containing medium. In addition, the multidifferentiation potential of UC-MSCs cultured in xeno- and serum-free StemMACS medium was maintained during long-term culture, but this potential was lost for adipogenic differentiation at P9. Moreover, secreted epidermal growth factor and vascular endothelial growth factor (VEGF)-A were detected in the conditioned media from UC-MSCs, whereas platelet-derived growth factor was not. Similar expression of these factors was observed in conditioned media of UC-MSCs cultured in StemMACS, but the VEGF level was higher in young UC-MSCs (P6) than in aged UC-MSCs cultured in FBS-supplemented Dulbecco's modified Eagle's medium/F12. Thus, StemMACS is better for UC-MSC expansion than conventional FBS-supplemented culture medium, especially when culturing UC-MSCs for real-world applications.

Substantial Overview on Mesenchymal Stem Cell Biological and Physical Properties as an Opportunity in Translational Medicine

Mesenchymal stem cells (MSC) have piqued worldwide interest for their extensive potential to treat a large array of clinical indications, their unique and controversial immunogenic and immune modulatory properties allowing ample discussions and debates for their possible applications. Emerging data demonstrating that the interaction of biomaterials and physical cues with MSC can guide their differentiation into specific cell lineages also provide new interesting insights for further MSC manipulation in different clinical applications. Moreover, recent discoveries of some regulatory molecules and signaling pathways in MSC niche that may regulate cell fate to distinct lineage herald breakthroughs in regenerative medicine. Although the advancement and success in the MSC field had led to an enormous increase in the amount of ongoing clinical trials, we still lack defined clinical therapeutic protocols. This review will explore the exciting opportunities offered by human and animal MSC, describing relevant biological properties of these cells in the light of the novel emerging evidence mentioned above while addressing the limitations and challenges MSC are still facing.

Effects of Human Fibroblast-Derived Extracellular Matrix on Mesenchymal Stem Cells

Stem cell fate is largely determined by the microenvironment called niche. The extracellular matrix (ECM), as a key component in the niche, is responsible for maintaining structural stability and regulating cell proliferation, differentiation, migration and other cellular activities. Each tissue has a unique ECM composition for its needs. Here we investigated the effect of a bioengineered human dermal fibroblast-derived ECM (hECM) on the regulation of human mesenchymal stem cell (hMSC) proliferation and multilineage differentiation. Human MSCs were maintained on hECM for two passages followed by the analysis of mRNA expression levels of potency- and lineage-specific markers to determine the capacity of MSC stemness and differentiation, respectively. Mesenchymal stem cells pre-cultured with or without hECM were then induced and analyzed for osteogenesis, adipogenesis and chondrogenesis. Our results showed that compared to MSCs maintained on control culture plates without hECM coating, cells on hECM-coated plates proliferated more rapidly with a higher percentage of cells in S phase of the cell cycle, resulting in an increase in the CD90⁺/CD105⁺/CD73⁺/CD45^- subpopulation. In addition, hECM downregulated osteogenesis and adipogenesis of hMSCs but significantly upregulated chondrogenesis with increased production of collagen type 2. In sum, our findings suggest that hECM may be used to culture hMSCs for the application of cartilage tissue engineering.

Ovine Mesenchymal Stromal Cells: Morphologic, Phenotypic and Functional Characterization for Osteochondral Tissue Engineering

INTRODUCTION

Knowledge of ovine mesenchymal stromal cells (oMSCs) is currently expanding. Tissue engineering combining scaffolding with oMSCs provides promising therapies for the treatment of osteochondral diseases.

PURPOSE

The aim was to isolate and characterize oMSCs from bone marrow aspirates (oBMSCs) and to assess their usefulness for osteochondral repair using β-tricalcium phosphate (bTCP) and type I collagen (Col I) scaffolds.

METHODS

Cells isolated from ovine bone marrow were characterized morphologically, phenotypically, and functionally. oBMSCs were cultured with osteogenic medium on bTCP and Col I scaffolds. The resulting constructs were evaluated by histology, immunohistochemistry and electron microscopy studies. Furthermore, oBMSCs were cultured on Col I scaffolds to develop an in vitro cartilage repair model that was assessed using a modified International Cartilage Research Society (ICRS) II scale.

RESULTS

oBMSCs presented morphology, surface marker pattern and multipotent capacities similar to those of human BMSCs. oBMSCs seeded on Col I gave rise to osteogenic neotissue. Assessment by the modified ICRS II scale revealed that fibrocartilage/hyaline cartilage was obtained in the in vitro repair model.

CONCLUSIONS

The isolated ovine cells were demonstrated to be oBMSCs. oBMSCs cultured on Col I sponges successfully synthesized osteochondral tissue. The data suggest that oBMSCs have potential for use in preclinical models prior to human clinical studies.

Serum and xeno-free, chemically defined, no-plate-coating-based culture system for mesenchymal stromal cells from the umbilical cord

OBJECTIVES

Umbilical cord mesenchymal stromal cells (UCMSCs) can be considered to become a new gold standard for MSC-based therapies. A serum and xeno-free, chemically defined and no-plate-coating-based culture system will greatly facilitate development of robust, clinically acceptable bioprocesses for reproducibly generating quality-assured UCMSCs.

MATERIALS AND METHODS

In this study, we report for the first time, such a serum-free, xeno-free, completely chemically defined and no-plate-coating-based culture system for the isolation and expansion of UCMSCs, whose biological characteristics were evaluated and compared with serum-containing medium (SCM) methods.

RESULTS

This culture system not only supported UCMSC primary cultures but also allowed for their expansion at low seeding density. Compared to SCM, UCMSCs in SFM exhibited (i) higher proliferative and colony-forming capacities; (ii) distinctly different morphologies; (iii) similar phenotype; (iv) similar pluripotency-associated marker expression; (v) superior osteogenic, but reduced adipogenic differentiation capacitities. In addition, UCMSCs cultured in SFM retained similar immunomodulatory properties to those in SCM.

CONCLUSIONS

Our findings demonstrate the feasibility of isolating and expanding UCMSCs in a completely serum-free, xeno-free, chemically defined and no-plate-coating-based culture system and represent an important step forward for development of robust, clinically acceptable bioprocesses for UCMSCs. Further, this provides a superior study platform for UCMSCs biology in a controlled environment.

Melatonin reverses flow shear stress-induced injury in bone marrow mesenchymal stem cells via activation of AMP-activated protein kinase signaling

Tissue-engineered heart valves (TEHVs) are a promising treatment for valvular heart disease, although their application is limited by high flow shear stress (FSS). Melatonin has a wide range of physiological functions and is currently under clinical investigation for expanded applications; moreover, extensive protective effects on the cardiovascular system have been reported. In this study, we investigated the protection conferred by melatonin supplementation against FSS-induced injury in bone marrow mesenchymal stem cells (BMSCs) and elucidated the potential mechanism in this process. Melatonin markedly reduced BMSC apoptotic death in a concentration-dependent manner while increasing the levels of transforming growth factor β (TGF-β), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and B-cell lymphoma 2 (Bcl2), and decreasing those of Bcl-2-associated X protein (Bax), p53 upregulated modulator of apoptosis (PUMA), and caspase 3. Notably, melatonin exerted its protective effects by upregulating the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), which promotes acetyl-CoA carboxylase (ACC) phosphorylation. Further molecular experiments revealed that luzindole, a nonselective antagonist of melatonin receptors, blocked the anti-FSS injury (anti-FSSI) effects of melatonin. Inhibition of AMPK by Compound C also counteracted the protective effects of melatonin, suggesting that melatonin reverses FSSI in BMSCs through the AMPK-dependent pathway. Overall, our findings indicate that melatonin contributes to the amelioration of FSS-induced BMSC injury by activating melatonin receptors and AMPK/ACC signaling. Our findings may provide a basis for the design of more effective strategies that promote the use of TEHCs in patients.

Mitochondrial transplantation for therapeutic use

Mitochondria play a key role in the homeostasis of the vast majority of the body's cells. In the myocardium where mitochondria constitute 30 % of the total myocardial cell volume, temporary attenuation or obstruction of blood flow and as a result oxygen delivery to myocardial cells (ischemia) severely alters mitochondrial structure and function. These alterations in mitochondrial structure and function occur during ischemia and continue after blood flow and oxygen delivery to the myocardium is restored, and significantly decrease myocardial contractile function and myocardial cell survival. We hypothesized that the augmentation or replacement of mitochondria damaged by ischemia would provide a mechanism to enhance cellular function and cellular rescue following the restoration of blood flow. To test this hypothesis we have used a model of myocardial ischemia and reperfusion. Our studies demonstrate that the transplantation of autologous mitochondria, isolated from the patient's own body, and then directly injected into the myocardial during early reperfusion augment the function of native mitochondria damaged during ischemia and enhances myocardial post-ischemic functional recovery and cellular viability. The transplanted mitochondria act both extracellularly and intracellularly. Extracellularly, the transplanted mitochondria enhance high energy synthesis and cellular adenosine triphosphate stores and alter the myocardial proteome. Once internalized the transplanted mitochondria rescue cellular function and replace damaged mitochondrial DNA. There is no immune or auto-immune reaction and there is no pro-arrhythmia as a result of the transplanted mitochondria. Our studies and those of others demonstrate that mitochondrial transplantation can be effective in a number of cell types and diseases. These include cardiac and skeletal muscle, pulmonary and hepatic tissue and cells and in neuronal tissue. In this review we discuss the mechanisms leading to mitochondrial dysfunction and the effects on cellular function. We provide a methodology for the isolation of mitochondria to allow for clinical relevance and we discuss the methods we and others have used for the uptake and internalization of mitochondria. We foresee that mitochondrial transplantation will be a valued treatment in the armamentarium of all clinicians and surgeons for the treatment of varied ischemic disorders, mitochondrial diseases and related disorders.

Modulation of human valve interstitial cell phenotype and function using a fibroblast growth factor 2 formulation

Valve interstitial cells (VICs) are fibroblastic in nature however in culture it is widely accepted that they differentiate into a myofibroblastic phenotype. This study assessed a fibroblast culture media formulation for its ability to maintain the phenotype and function of VICs as in the intact healthy valve. Normal human VICs were cultured separately in standard DMEM and in fibroblast media consisting of FGF2 (10ng/ml), insulin (50ng/ml) and 2% FCS for at least a week. Cell morphology, aspect ratio, size, levels and distribution of protein expression, proliferation, cell cycle, contraction and migration were assessed. Some VICs and some valve endothelial cells expressed FGF2 in valve tissue and this expression was increased in calcified valves. VICs in DMEM exhibited large, spread cells whereas VICs in fibroblast media were smaller, elongated and spindly. Aspect ratio and size were both significantly higher in DMEM (p<0.01). The level of expression of α-SMA was significantly reduced in fibroblast media at day 2 after isolation (p<0.01) and the expression of α-SMA, SM22 and EDA-fibronectin was significantly reduced in fibroblast media at days 7 and 12 post-isolation (p<0.01). Expression of cytoskeletal proteins, bone marker proteins and extracellular matrix proteins was reduced in fibroblast media. Proliferation of VICs in fibroblast media was significantly reduced at weeks 1 (p<0.05) and 2 (p<0.01). Collagen gel contraction was significantly reduced in fibroblast media (p<0.05). VICs were found to have significantly fewer and smaller focal adhesions in fibroblast media (p<0.01) with significantly fewer supermature focal adhesions in fibroblast media (p<0.001). Ultrastructurally, VICs in fibroblast media resembled native VICs from intact valves. VICs in fibroblast media demonstrated a slower migratory ability after wounding at 72 hours (p<0.01). Treatment of human VICs with this fibroblast media formulation has the ability to maintain and to dedifferentiate the VICs back to a fibroblastic phenotype with phenotypic and functional characteristics ascribed to cells in the intact valve. This methodology is fundamental in the study of normal valve biology, pathology and in the field of tissue engineering.

Comparison of Mesenchymal Stem Cell Source Differentiation Toward Human Pediatric Aortic Valve Interstitial Cells within 3D Engineered Matrices

Living tissue-engineered heart valves (TEHV) would be a major benefit for children who require a replacement with the capacity for growth and biological integration. A persistent challenge for TEHV is accessible human cell source(s) that can mimic native valve cell phenotypes and matrix remodeling characteristics that are essential for long-term function. Mesenchymal stem cells derived from bone marrow (BMMSC) or adipose tissue (ADMSC) are intriguing cell sources for TEHV, but they have not been compared with pediatric human aortic valve interstitial cells (pHAVIC) in relevant 3D environments. In this study, we compared the spontaneous and induced multipotency of ADMSC and BMMSC with that of pHAVIC using different induction media within three-dimensional (3D) bioactive hybrid hydrogels with material modulus comparable to that of aortic heart valve leaflets. pHAVIC possessed some multi-lineage differentiation capacity in response to induction media, but limited to the earliest stages and much less potent than either ADMSC or BMMSC. ADMSC expressed cell phenotype markers more similar to pHAVIC when conditioned in basic fibroblast growth factor (bFGF) containing HAVIC growth medium, while BMMSC generally expressed similar extracellular matrix remodeling characteristics to pHAVIC. Finally, we covalently attached bFGF to PEG monoacrylate linkers and further covalently immobilized in the 3D hybrid hydrogels. Immobilized bFGF upregulated vimentin expression and promoted the fibroblastic differentiation of pHAVIC, ADMSC, and BMMSC. These findings suggest that stem cells retain a heightened capacity for osteogenic differentiation in 3D culture, but can be shifted toward fibroblast differentiation through matrix tethering of bFGF. Such a strategy is likely important for utilizing stem cell sources in heart valve tissue engineering applications.

Mesenchymal stem cell therapies in the treatment of musculoskeletal diseases

The application of regenerative strategies to musculoskeletal ailments offers extraordinary promise to transform management of the conditions of numerous patients. The use of cell-based therapies and adjunct strategies is under active investigation for injuries and illnesses affecting bones, joints, tendons, and skeletal muscle. Of particular interest to the field is the mesenchymal stem cell, an adult stem cell found in bone marrow and adipose tissue. This cell type can be expanded ex vivo, has allogeneic application, and has the capacity for engraftment and differentiation into mesodermal lineages. Also of major interest in the field is the use of platelet-rich plasma, a strategy to concentrate endogenous cytokines and growth factors with reparative potential. Here we review the biological basis, clinical studies, safety, and current state of mesenchymal stem cell and platelet-rich plasma therapies in the treatment of musculoskeletal disease.

Scaffolds for tissue engineering of cardiac valves

Tissue engineered heart valves offer a promising alternative for the replacement of diseased heart valves avoiding the limitations faced with currently available bioprosthetic and mechanical heart valves. In the paradigm of tissue engineering, a three-dimensional platform - the so-called scaffold - is essential for cell proliferation, growth and differentiation, as well as the ultimate generation of a functional tissue. A foundation for success in heart valve tissue engineering is a recapitulation of the complex design and diverse mechanical properties of a native valve. This article reviews technological details of the scaffolds that have been applied to date in heart valve tissue engineering research.

In situ tissue regeneration: chemoattractants for endogenous stem cell recruitment

Tissue engineering uses cells, signaling molecules, and/or biomaterials to regenerate injured or diseased tissues. Ex vivo expanded mesenchymal stem cells (MSC) have long been a cornerstone of regeneration therapies; however, drawbacks that include altered signaling responses and reduced homing capacity have prompted investigation of regeneration based on endogenous MSC recruitment. Recent successful proof-of-concept studies have further motivated endogenous MSC recruitment-based approaches. Stem cell migration is required for morphogenesis and organogenesis during development and for tissue maintenance and injury repair in adults. A biomimetic approach to in situ tissue regeneration by endogenous MSC requires the orchestration of three main stages: MSC recruitment, MSC differentiation, and neotissue maturation. The first stage must result in recruitment of a sufficient number of MSC, capable of effecting regeneration, to the injured or diseased tissue. One of the challenges for engineering endogenous MSC recruitment is the selection of effective chemoattractant(s). The objective of this review is to synthesize and evaluate evidence of recruitment efficacy by reported chemoattractants, including growth factors, chemokines, and other more recently appreciated MSC chemoattractants. The influence of MSC tissue sources, cell culture methods, and the in vitro and in vivo environments is discussed. This growing body of knowledge will serve as a basis for the rational design of regenerative therapies based on endogenous MSC recruitment. Successful endogenous MSC recruitment is the first step of successful tissue regeneration.

Transplantation of autologously derived mitochondria protects the heart from ischemia-reperfusion injury

Mitochondrial damage and dysfunction occur during ischemia and modulate cardiac function and cell survival significantly during reperfusion. We hypothesized that transplantation of autologously derived mitochondria immediately prior to reperfusion would ameliorate these effects. New Zealand White rabbits were used for regional ischemia (RI), which was achieved by temporarily snaring the left anterior descending artery for 30 min. Following 29 min of RI, autologously derived mitochondria (RI-mitochondria; 9.7 ± 1.7 × 10(6)/ml) or vehicle alone (RI-vehicle) were injected directly into the RI zone, and the hearts were allowed to recover for 4 wk. Mitochondrial transplantation decreased (P < 0.05) creatine kinase MB, cardiac troponin-I, and apoptosis significantly in the RI zone. Infarct size following 4 wk of recovery was decreased significantly in RI-mitochondria (7.9 ± 2.9%) compared with RI-vehicle (34.2 ± 3.3%, P < 0.05). Serial echocardiograms showed that RI-mitochondria hearts returned to normal contraction within 10 min after reperfusion was started; however, RI-vehicle hearts showed persistent hypokinesia in the RI zone at 4 wk of recovery. Electrocardiogram and optical mapping studies showed that no arrhythmia was associated with autologously derived mitochondrial transplantation. In vivo and in vitro studies show that the transplanted mitochondria are evident in the interstitial spaces and are internalized by cardiomyocytes 2-8 h after transplantation. The transplanted mitochondria enhanced oxygen consumption, high-energy phosphate synthesis, and the induction of cytokine mediators and proteomic pathways that are important in preserving myocardial energetics, cell viability, and enhanced post-infarct cardiac function. Transplantation of autologously derived mitochondria provides a novel technique to protect the heart from ischemia-reperfusion injury.

Platelet gel supernatant as a potential tool to repopulate acellular heart valves

OBJECTIVE

The aim of this study was to repopulate decellularized heart valve matrices with ovine mesenchymal stem cells (oMSCs) by the use of platelet gel (PG) supernatant, a storage vehicle for growth factors.

METHODS

oMSCs were exposed to different concentrations of PG-released supernatant and cell proliferation was evaluated using the MTS assay. oMSC motility and invasiveness were assayed using a Boyden chamber. A quantitative sandwich enzyme immunoassay was used to examine amounts of bFGF and TGF-β1 in the PG supernatant. Repopulation of acellular heart valve matrices was stimulated by seeding matrices with oMSCs supplemented with the PG supernatant.

RESULTS

The most significant increase in proliferation induced by PG supernatant appeared at 1 × 10(5) plts/ml concentration. Higher concentrations evoked reduction of the stimulatory process. oMSC motility was most significantly stimulated at 1 × 10(6) plts/ml. Stimulating invasiveness of oMSCs needed the much higher concentration of 2 × 10(6) plts/ml. Immunoassays revealed that sheep PG supernatant contains 184.8 pg/ml bFGF and 60.5 ng/ml TGF-β1. Moreover, repopulation of acellular heart valve matrices was significantly enhanced by PG supernatant addition and resulted in upregulation of the myofibroblast marker alpha-smooth muscle actin.

CONCLUSIONS

Growth factors released from platelets had the potential to induce cell repopulation in a heart valve tissue engineering procedure, through stimulation of mesenchymal stem-cell migration and invasion.