Mesenchymal stem cells and progenitor cells in connective tissue engineering and regenerative medicine: is there a future for transplantation?

Microenvironmental interference with intra-articular stem cell regeneration influences the onset and progression of arthritis

Studies have indicated that the preservation of joint health and the facilitation of damage recovery are predominantly contingent upon the joint's microenvironment, including cell-cell interactions, the extracellular matrix's composition, and the existence of local growth factors. Mesenchymal stem cells (MSCs), which possess the capacity to self-renew and specialize in many directions, respond to cues from the microenvironment, and aid in the regeneration of bone and cartilage, are crucial to this process. Changes in the microenvironment (such as an increase in inflammatory mediators or the breakdown of the extracellular matrix) in the pathological context of arthritis might interfere with stem cell activation and reduce their ability to regenerate. This paper investigates the potential role of joint microenvironmental variables in promoting or inhibiting the development of arthritis by influencing stem cells' ability to regenerate. The present status of research on stem cell activity in the joint microenvironment is also outlined, and potential directions for developing new treatments for arthritis that make use of these intervention techniques to boost stem cell regenerative potential through altering the intra-articular environment are also investigated. This review's objectives are to investigate these processes, offer fresh perspectives, and offer a solid scientific foundation for the creation of arthritic treatment plans in the future.

Dental Pulp Cell Transplantation Combined with Regenerative Endodontic Procedures Promotes Dentin Matrix Formation in Mature Mouse Molars

Regenerative endodontic procedures (REPs) are promising for dental pulp tissue regeneration; however, their application in permanent teeth remains challenging. We assessed the potential combination of an REP and local dental pulp cell (DPC) transplantation in the mature molars of C57BL/6 mice with (REP + DPC group) or without (REP group) transplantation of DPCs from green fluorescent protein (GFP) transgenic mice. After 4 weeks, the regenerated tissue was evaluated by micro-computed tomography and histological analyses to detect odontoblasts, vasculogenesis, and neurogenesis. DPCs were assessed for mesenchymal and pluripotency markers. Four weeks after the REP, the molars showed no signs of periapical lesions, and both the REP and REP + DPC groups exhibited a pulp-like tissue composed of a cellular matrix with vessels surrounded by an eosin-stained acellular matrix that resembled hard tissue. However, the REP + DPC group had a broader cellular matrix and uniquely contained odontoblast-like cells co-expressing GFP. Vasculogenesis and neurogenesis were detected in both groups, with the former being more prominent in the REP + DPC group. Overall, the REP was achieved in mature mouse molars and DPC transplantation improved the outcomes by inducing the formation of odontoblast-like cells and greater vasculogenesis.

Mesenchymal Stem Cells: Generalities and Clinical Significance in Feline and Canine Medicine

Mesenchymal stem cells (MSCs) are multipotent cells: they can proliferate like undifferentiated cells and have the ability to differentiate into different types of cells. A considerable amount of research focuses on the potential therapeutic benefits of MSCs, such as cell therapy or tissue regeneration, and MSCs are considered powerful tools in veterinary regenerative medicine. They are the leading type of adult stem cells in clinical trials owing to their immunosuppressive, immunomodulatory, and anti-inflammatory properties, as well as their low teratogenic risk compared with pluripotent stem cells. The present review details the current understanding of the fundamental biology of MSCs. We focus on MSCs' properties and their characteristics with the goal of providing an overview of therapeutic innovations based on MSCs in canines and felines.

Clinical trials using dental stem cells: 2022 update

For nearly 20 years, dental stem cells (DSCs) have been successfully isolated from mature/immature teeth and surrounding tissue, including dental pulp of permanent teeth and exfoliated deciduous teeth, periodontal ligaments, dental follicles, and gingival and apical papilla. They have several properties (such as self-renewal, multidirectional differentiation, and immunomodulation) and exhibit enormous potential for clinical applications. To date, many clinical articles and clinical trials using DSCs have reported the treatment of pulpitis, periapical lesions, periodontitis, cleft lip and palate, acute ischemic stroke, and so on, and DSC-based therapies obtained satisfactory effects in most clinical trials. In these studies, no adverse events were reported, which suggested the safety of DSC-based therapy. In this review, we outline the characteristics of DSCs and summarize clinical trials and their safety as DSC-based therapies. Meanwhile, we also present the current limitations and perspectives of DSC-based therapy (such as harvesting DSCs from inflamed tissue, applying DSC-conditioned medium/DSC-derived extracellular vesicles, and expanding-free strategies) to provide a theoretical basis for their clinical applications.

Co-Electrospun Silk Fibroin and Gelatin Methacryloyl Sheet Seeded with Mesenchymal Stem Cells for Tendon Regeneration

Silk fibroin (SF) is a promising biomaterial for tendon repair, but its relatively rigid mechanical properties and low cell affinity have limited its application in regenerative medicine. Meanwhile, gelatin-based polymers have advantages in cell attachment and tissue remodeling but have insufficient mechanical strength to regenerate tough tissue such as tendons. Taking these aspects into account, in this study, gelatin methacryloyl (GelMA) is combined with SF to create a mechanically strong and bioactive nanofibrous scaffold (SG). The mechanical properties of SG nanofibers can be flexibly modulated by varying the ratio of SF and GelMA. Compared to SF nanofibers, mesenchymal stem cells (MSCs) seeded on SG fibers with optimal composition (SG7) exhibit enhanced growth, proliferation, vascular endothelial growth factor production, and tenogenic gene expression behavior. Conditioned media from MSCs cultured on SG7 scaffolds can greatly promote the migration and proliferation of tenocytes. Histological analysis and tenogenesis-related immunofluorescence staining indicate SG7 scaffolds demonstrate enhanced in vivo tendon tissue regeneration compared to other groups. Therefore, rational combinations of SF and GelMA hybrid nanofibers may help to improve therapeutic outcomes and address the challenges of tissue-engineered scaffolds for tendon regeneration.

A critical review of fibrous polyurethane-based vascular tissue engineering scaffolds

Certain polymeric materials such as polyurethanes (PUs) are the most prevalent class of used biomaterials in regenerative medicine and have been widely explored as vascular substitutes in several animal models. It is thought that PU-based biomaterials possess suitable hemo-compatibility with comparable performance related to the normal blood vessels. Despite these advantages, the possibility of thrombus formation and restenosis limits their application as artificial functional vessels. In this regard, various surface modification approaches have been developed to enhance both hemo-compatibility and prolong patency. While critically reviewing the recent advances in vascular tissue engineering, mainly PU grafts, this paper summarizes the application of preferred cell sources to vascular regeneration, physicochemical properties, and some possible degradation mechanisms of PU to provide a more extensive perspective for future research.

Progress and prospect of stem cell therapy for diabetic erectile dysfunction

Diabetic erectile dysfunction (DED) is a common complication of diabetes mellitus, significantly impairing the quality of life of patients. The conventional clinical treatment still has limitations. Stem cells (SCs), as a type of cells with multidirectional or directional differentiation capability and sustainable self-renewal potential, are widely used in regenerative medicine and tissue engineering. With the continuous update of regenerative medicine theory and the success of animal experiments, SCs as a treatment for male erectile dysfunction, especially DED, have attracted widespread attention because of curable possibility. This review focus on the current progress in the clinical application of SC treatment for DED. Moreover, we summarize the development prospects of SCs in the field of DMED therapy.

Intravenous SPION-labeled adipocyte-derived stem cells targeted to the brain by magnetic attraction in a rat stroke model: An ultrastructural insight into cell fate within the brain

Mesenchymal stem cell therapy after stroke is a promising option investigated in animal models and clinical trials. The intravenous route is commonly used in clinical settings guaranteeing an adequate safety profile although low yields of engraftment. In this report, rats subjected to ischemic stroke were injected with adipose-derived stem cells (ADSCs) labeled with superparamagnetic iron oxide nanoparticles (SPIONs) applying an external magnetic field in the skull to retain the cells. Although most published studies demonstrate viability of ADSCs, only a few have used ultrastructural techniques. In our study, the application of a local magnetic force resulted in a tendency for higher yields of SPION-ADSCs targeting the brain. However, grafted cells displayed morphological signs of death, one day after administration, and correlative microscopy showed active microglia and astrocytes associated in the process of scavenging. Thus, we conclude that, although successfully targeted within the brain, SPION-ADSCs viability was rapidly compromised.

Improved drug delivery and accelerated diabetic wound healing by chondroitin sulfate grafted alginate-based thermoreversible hydrogels

Injectable hydrogels with multifunctional tunable properties comprising biocompatibility, anti-oxidative, anti-bacterial, and/or anti-infection are highly preferred to efficiently promote diabetic wound repair and its development remains a challenge. In this study, we report chondroitin sulphate (CS) and sodium alginate (SA)-based injectable hydrogel using solvent casting method loaded with curcumin that could potentiate reepithelization, increase angiogenesis, and collagen deposition at wound microenvironment to endorse healing cascade. The physical interaction and self-assembly of chondroitin sulfate grafted alginate (CS-Alg-g-PF127) hydrogel were confirmed using nuclear magnetic resonance (¹H NMR) and Fourier transformed infrared spectroscopy (FT-IR), and cytocompatibility was confirmed by fibroblast viability assay. The Masson's trichrome (MT) and hematoxylin and eosin (H&E) results revealed that blank chondroitin sulfate grafted alginate (CS-Alg-g-PF127) and CUR loaded CS-Alg-g-PF127 hydrogel had promising tissue regenerative ability, and showing enhanced wound healing compared to other treatment groups. The controlled release of CUR from injectable hydrogel was evaluated by drug release studies and pharmacokinetic profile (PK) using high-performance liquid chromatography (HPLC) that exhibited the mean residence time (MRT) and area under the curve (AUC) was increased up to 16.18 h and 203.64 ± 30.1 μg/mL*h, respectively. Cytotoxicity analysis of the injectable hydrogels using 3 T3-L1 fibroblasts cells and in vivo toxicity evaluated by subcutaneous injection for 24 h followed by histological examination, confirmed good biocompatibility of CUR loaded CS-Alg-g-PF127 hydrogel. Interestingly, the results of in vivo wound healing by injectable hydrogel showed the upregulation of fibroblasts-like cells, collagen deposition, and differentiated keratinocytes stimulating dermo-epidermal junction, which might endorse that they are potential candidates for excisional wound healing models.

Human adventitial pericytes provide a unique source of anti-calcific cells for cardiac valve engineering: Role of microRNA-132-3p

AIMS

Tissue engineering aims to improve the longevity of prosthetic heart valves. However, the optimal cell source has yet to be determined. This study aimed to establish a mechanistic rationale supporting the suitability of human adventitial pericytes (APCs).

METHODS AND RESULTS

APCs were immunomagnetically sorted from saphenous vein leftovers of patients undergoing coronary artery bypass graft surgery and antigenically characterized for purity. Unlike bone marrow-derived mesenchymal stromal cells (BM-MSCs), APCs were resistant to calcification and delayed osteochondrogenic differentiation upon high phosphate (HP) induction, as assessed by cytochemistry and expression of osteogenic markers. Moreover, glycolysis was activated during osteogenic differentiation of BM-MSCs, whereas APCs showed no increase in glycolysis upon HP challenge. The microRNA-132-3p (miR-132), a known inhibitor of osteogenesis, was found constitutively expressed by APCs and upregulated following HP stimulation. The anti-calcific role of miR-132 was further corroborated by in silico analysis, luciferase assays in HEK293 cells, and transfecting APCs with miR-132 agomir and antagomir, followed by assessment of osteochondrogenic markers. Interestingly, treatment of swine cardiac valves with APC-derived conditioned medium conferred them with resistance to HP-induced osteogenesis, with this effect being negated when using the medium of miR-132-silenced APCs. Additionally, as an initial bioengineering step, APCs were successfully engrafted onto pericardium sheets, where they proliferated and promoted aortic endothelial cells attraction, a process mimicking valve endothelialization.

CONCLUSIONS

Human APCs are resistant to calcification compared with BM-MSCs and convey the anti-calcific phenotype to heart valves through miR-132. These findings may open new important avenues for prosthetic valve cellularization.

Mesenchymal stem cell spheroids incorporated with collagen and black phosphorus promote osteogenesis of biodegradable hydrogels

Mesenchymal stem cell (MSC)-spheroids have sparked significant interest in bone tissue engineering due to their resemblance to natural bone tissue, especially in terms of cell-cell and cell-extracellular matrix interactions. Many biomaterials or biomolecules have been incorporated into MSC-spheroids to enhance their osteogenic abilities. In this respect, we assessed the osteogenic responses of MSC spheroids leveraged through the unique combination of collagen and black phosphorus (BP). The MSC spheroids were successfully constructed with 6 μg/mL collagen and/or a concentration gradient (0 μg/mL, 4 μg/mL, 8 μg/mL, and 16 μg/mL) of BP and were evaluated for MSC viability and their osteogenic differentiation over a time period of 14 days. Improved MSC viability and osteogenic ability were observed for the spheroids with collagen and BP at the concentration of 4 μg/mL and 8 μg/mL. Next, blank spheroids (Control) or the optimized MSC spheroids with 6 μg/mL collagen and 4 μg/mL BP (Col+BP4) were further encapsulated into two types of hydrogel scaffolds: porous oligo[poly(ethylene glycol) fumarate] (OPF) hydrogel and hydroxyapatite-collagen I scaffold (HE-COL). The osteogenic abilities of these four groups were evaluated after 14 and 21 days of osteogenic induction. The MSC spheroids incorporated with collagen and BP implanted into OPF porous hydrogel (Col+BP/OPF) elicited a higher expression of Runx2, osteopontin, and alkaline phosphatase than blank spheroids implanted into OPF porous hydrogel (Control/OPF). Enhanced osteogenesis was also observed in the Col+BP/HE-COL group as compared to Control/HE-COL. Taken together, the results from this study showed the perspectives of collagen and BP incorporated MSC spheroids for the development of injectable cellular therapies for bone regeneration.

Comparative analysis of mesenchymal stromal cells derived from rabbit bone marrow and Wharton's jelly for adipose tissue engineering

Purpose: To investigate the proliferative, adipogenic, and immunological properties of rabbit Mesenchymal stromal cells (MSCs) derived from bone marrow and umbilical cord Wharton's jelly.Materials and Methods: We extracted rabbit MSCs from bone marrow (BMSCs) and umbilical cord Wharton's jelly (WJ-MSCs). Both BMSCs and WJ-MSCs underwent adipogenic differentiation for 2 weeks, and then were transferred to non-inductive complete medium. Their adipogenic capacities were examined by histomorphometry and quantitative RT-PCR (qRT-PCR). The immunological markers were determined by mRNA expression of MHC-Ia, MHC-II, and RLA-DRA by qRT-PCR and protein expression of MHC-II by immunofluorescent staining. The proliferative capacities of adipogenic MSCs were also examined by counting kit-8 experiment and cell population doubling time.Results: We found that adipogenic differentiation increased the mRNA expression levels of adipogenic and immunological markers. The protein expression levels of MHC-II also increased after adipogenic differentiation in both groups. The adipogenic BMSCs showed higher mRNA expression levels of adipogenic and immunological markers. Removal of adipogenic agents after 2 weeks of adipo-differentiation inversely decreased the expression of immunological and adipogenic markers. The adipo-differentiation could decreased the proliferative capacities of both MSCs, but the adipogenic WJ-MSCs showed significantly higher proliferative capacities than BMSCs.Conclusions: Adipogenic differentiation increased the immunogenicity of both BMSCs and WJ-MSCs, and dedifferentiation inversely decreased their immunogenicity. Adipogenic WJ-MSCs showed significantly higher proliferative and immunoprivileged capacities than BMSCs, and the dedifferentiated BMSCs showed almost the same adipogenic capacity as WJ-MSCs. WJ-MSCs were more suitable than BMSCs for adipose tissue engineering.

A new waterborne chitosan-based polyurethane hydrogel as a vehicle to transplant bone marrow mesenchymal cells improved wound healing of ulcers in a diabetic rat model

Foot ulcers, a common complication of diabetes, can cause physical incapacity and are derived from several factors, including poor wound healing. New therapeutic strategies are needed to minimize this complication for the sake of patients' health. We therefore developed a new chitosan- polyurethane hydrogel membrane (HPUC) and the test results confirmed that HPUC present low cytotoxicity and improved wound healing when used with mononuclear bone marrow fraction cells in the diabetic rat model. The biodegradable hydrogels were produced in block copolymer networks with a combination of chitosan blocks and biodegradable polyurethane. The membranes were characterized by FTIR, ¹³C-NMR and thermogravimetry. Swelling and hydrolytic degradation were also evaluated. The non-solubility of the membranes in good solvents and the chemical characterization confirmed that the network structure was formed between the PU and the chitosan through urea/urethane bonds. The findings confirm that the HPUC have interesting properties that make them suitable for wound healing applications.

Comparison of gingiva-derived and bone marrow mesenchymal stem cells for osteogenesis

Presently, bone marrow is considered as a prime source of mesenchymal stem cells; however, there are some drawbacks and limitations. Compared with other mesenchymal stem cell (MSC) sources, gingiva-derived mesenchymal stem cells (GMSCs) are abundant and easy to obtain through minimally invasive cell isolation techniques. In this study, MSCs derived from gingiva and bone marrow were isolated and cultured from mice. GMSCs were characterized by osteogenic, adipogenic and chondrogenic differentiation, and flow cytometry. Compared with bone marrow MSCs (BMSCs), the proliferation capacity was judged by CCK-8 proliferation assay. Osteogenic differentiation was assessed by ALP staining, ALP assay and Alizarin red staining. RT-qPCR was performed for ALP, OCN, OSX and Runx2. The results indicated that GMSCs showed higher proliferative capacity than BMSCs. GMSCs turned more positive for ALP and formed a more number of mineralized nodules than BMSCs after osteogenic induction. RT-qPCR revealed that the expression of ALP, OCN, OSX and Runx2 was significantly increased in the GMSCs compared with that in BMSCs. Moreover, it was found that the number of CD90-positive cells in GMSCs elevated more than that of BMSCs during osteogenic induction. Taking these results together, it was indicated that GMSCs might be a promising source in the future bone tissue engineering.

Phase I/II Study of Safety and Preliminary Efficacy of Intravenous Allogeneic Mesenchymal Stem Cells in Chronic Stroke

Background and Purpose- Stroke is a leading cause of long-term disability. Limited treatment options exist for patients with chronic stroke and substantial functional deficits. The current study examined safety and preliminary efficacy estimates of intravenous allogeneic mesenchymal stem cells in this population. Methods- Entry criteria included ischemic stroke >6 months prior and substantial impairment (National Institutes of Health Stroke Scale score ≥6) and disability. Enrollees received a single intravenous dose of allogeneic ischemia-tolerant mesenchymal stem cells. Phase 1 used a dose-escalation design (3 tiers, n=5 each). Phase 2 was an expanded safety cohort. The primary end point was safety over 1-year. Secondary end points examined behavioral change. Results- In phase 1 (n=15), each dose (0.5, 1.0, and 1.5 million cells/kg body weight) was found safe, so phase 2 subjects (n=21) received 1.5 million cells/kg. At baseline, subjects (n=36) averaged 4.2±4.6 years poststroke, age 61.1±10.8 years, National Institutes of Health Stroke Scale score 8 (6.5-10), and Barthel Index 65±29. Two were lost to follow-up, one was withdrawn and 2 died (unrelated to study treatment). Of 15 serious adverse events, none was possibly or probably related to study treatment. Two mild adverse events were possibly related to study treatment, a urinary tract infection and intravenous site irritation. Treatment was safe based on serial exams, electrocardiograms, laboratory tests, and computed tomography scans of chest/abdomen/pelvis. All behavioral end points showed significant gains over the 12-months of follow-up. For example, Barthel Index scores increased by 6.8±11.4 points (mean±SD) at 6-months (P=0.002) and by 10.8±15.5 points at 12-months (P<0.001) post-infusion; the proportion of patients achieving excellent functional outcome (Barthel score ≥95) increased from 11.4% at baseline to 27.3% at 6-months and to 35.5% at 12-months. Conclusions- Intravenous transfusion of allogeneic ischemia-tolerant mesenchymal stem cell in patients with chronic stroke and substantial functional deficits was safe and suggested behavioral gains. These data support proceeding to a randomized, placebo-controlled study of this therapy in this population. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT01297413.

Hyaluronan-Based Grafting Strategies for Liver Stem Cell Therapy and Tracking Methods

Cell adhesion is essential for survival, it plays important roles in physiological cell functions, and it is an innovative target in regenerative medicine. Among the molecular interactions and the pathways triggered during cell adhesion, the binding of cluster of differentiation 44 (CD44), a cell-surface glycoprotein involved in cell-cell interactions, to hyaluronic acid (HA), a major component of the extracellular matrix, is a crucial step. Cell therapy has emerged as a promising treatment for advanced liver diseases; however, so far, it has led to low cell engraftment and limited cell repopulation of the target tissue. Currently, different strategies are under investigation to improve cell grafting in the liver, including the use of organic and inorganic biomatrices that mimic the microenvironment of the extracellular matrix. Hyaluronans, major components of stem cell niches, are attractive candidates for coating stem cells since they improve viability, proliferation, and engraftment in damaged livers. In this review, we will discuss the new strategies that have been adopted to improve cell grafting and track cells after transplantation.

Bone Marrow Transplantation for Treatment of the Col1a2+/G610C Osteogenesis Imperfecta Mouse Model

Bone marrow transplantation (BMT) of healthy donor cells has been postulated as a strategy for treating osteogenesis imperfecta (OI) and other bone fragility disorders. The effect of engraftment by tail vein injection and/or marrow ablation by 6 Gy whole body irradiation were tested in Col1a2^+/G610C (OI) mice as a model of mild-moderate OI. Dual-emission X-ray absorptiometry, microCT, and 4-point bending were used to measure bone volume (BV), bone mineral density (BMD), and biomechanical strength. BV, BMD, and mechanical strength were reduced in OI mice compared to wild type (WT) controls. BMT with and without irradiation yielded no difference in BV and BMD outcomes for both OI and WT mice, at 3 weeks. Transplantation of OI cells into OI mice to test for paracrine effects of BMT also showed no difference with non-transplanted OI mice. In a parallel cell tracking study, donor marrow was taken from transgenic mice constitutively expressing tdTomato and transplanted into WT mice. Lineage tracking demonstrated that irradiation considerably enhanced engraftment of tdTomato+ cells. However, tdTomato+ cells predominantly expressed TRAP and not AP, indicating engrafted donor cells were chiefly from the hematopoietic lineages. These data show that whole marrow transplantation fails to rescue the bone phenotype of Col1a2^+/G610C (OI) mice and that osteopoietic engraftment is not significantly enhanced by irradiation. These findings are highly relevant to modern approaches focused on the gene repair of patient cells ex vivo and their subsequent reintroduction into the osteopoietic compartment via the circulation.

Stem cells: past, present, and future

In recent years, stem cell therapy has become a very promising and advanced scientific research topic. The development of treatment methods has evoked great expectations. This paper is a review focused on the discovery of different stem cells and the potential therapies based on these cells. The genesis of stem cells is followed by laboratory steps of controlled stem cell culturing and derivation. Quality control and teratoma formation assays are important procedures in assessing the properties of the stem cells tested. Derivation methods and the utilization of culturing media are crucial to set proper environmental conditions for controlled differentiation. Among many types of stem tissue applications, the use of graphene scaffolds and the potential of extracellular vesicle-based therapies require attention due to their versatility. The review is summarized by challenges that stem cell therapy must overcome to be accepted worldwide. A wide variety of possibilities makes this cutting edge therapy a turning point in modern medicine, providing hope for untreatable diseases.

Cell Sources for Tissue Engineering Strategies to Treat Calcific Valve Disease

Cardiovascular calcification is an independent risk factor and an established predictor of adverse cardiovascular events. Despite concomitant factors leading to atherosclerosis and heart valve disease (VHD), the latter has been identified as an independent pathological entity. Calcific aortic valve stenosis is the most common form of VDH resulting of either congenital malformations or senile “degeneration.” About 2% of the population over 65 years is affected by aortic valve stenosis which represents a major cause of morbidity and mortality in the elderly. A multifactorial, complex and active heterotopic bone-like formation process, including extracellular matrix remodeling, osteogenesis and angiogenesis, drives heart valve “degeneration” and calcification, finally causing left ventricle outflow obstruction. Surgical heart valve replacement is the current therapeutic option for those patients diagnosed with severe VHD representing more than 20% of all cardiac surgeries nowadays. Tissue Engineering of Heart Valves (TEHV) is emerging as a valuable alternative for definitive treatment of VHD and promises to overcome either the chronic oral anticoagulation or the time-dependent deterioration and reintervention of current mechanical or biological prosthesis, respectively. Among the plethora of approaches and stablished techniques for TEHV, utilization of different cell sources may confer of additional properties, desirable and not, which need to be considered before moving from the bench to the bedside. This review aims to provide a critical appraisal of current knowledge about calcific VHD and to discuss the pros and cons of the main cell sources tested in studies addressing in vitro TEHV.

Restoring the biophysical properties of decellularized patches through recellularization

Various extracellular matrix (ECM) scaffolds, isolated through decellularization, were suggested as ideal biomimetic materials for 'Functional tissue engineering' (FTE). The decellularization process comprises a compromise between damaging and preserving the ultrastructure and composition of ECM-previously shown to affect cell survival, proliferation, migration, organization, differentiation and maturation. Inversely, the effects of cells on the ECM constructs' biophysical properties, under physiological-like conditions, remain still largely unknown. We hypothesized that by re-cellularizing porcine cardiac ECM (pcECM, as a model scaffold) some of the original biophysical properties of the myocardial tissue can be restored, which are related to the scaffold's surface and the bulk modifications consequent to cellularization. We performed a systematic biophysical assessment of pcECM scaffolds seeded with human mesenchymal stem cells (MSCs), a common multipotent cell source in cardiac regenerative medicine. We report a new type of FTE study in which cell interactions with a composite-scaffold were evaluated from the perspective of their contribution to the biophysical properties of the construct surface (FTIR, WETSEM™) and bulk (DSC, TGA, and mechanical testing). The results obtained were compared with acellular pcECM and native ventricular tissue serving as negative and positive controls, respectively. MSC recellularization resulted in an inter-fiber plasticization effect, increased protein density, masking of acylated glycosaminoglycans (GAGs) and active pcECM remodelling which further stabilized the reseeded construct and increased its denaturation resistance. The systematic approach presented herein, therefore, identifies cells as "biological plasticizers" and yields important methodologies, understanding, and data serving both as a reference as well as possible 'design criteria' for future studies in FTE.

Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)

Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.

Enhanced metastatic capacity of breast cancer cells after interaction and hybrid formation with mesenchymal stroma/stem cells (MSC)

Background

Fusion of breast cancer cells with tumor-associated populations of the microenvironment including mesenchymal stroma/stem-like cells (MSC) represents a rare event in cell communication whereby the metastatic capacity of those hybrid cells remains unclear.

Methods

Functional changes were investigated in vitro and in vivo following spontaneous fusion and hybrid cell formation between primary human MSC and human MDA-MB-231 breast cancer cells. Thus, lentiviral eGFP-labeled MSC and breast cancer cells labeled with mcherry resulted in dual-fluorescing hybrid cells after co-culture.

Results

Double FACS sorting and single cell cloning revealed two different aneuploid male hybrid populations (MDA-hyb1 and MDA-hyb2) with different STR profiles, pronounced telomerase activities, and enhanced proliferative capacities as compared to the parental cells. Microarray-based mRNA profiling demonstrated marked regulation of genes involved in epithelial-mesenchymal transition and increased expression of metastasis-associated genes including S100A4. In vivo studies following subcutaneous injection of the breast cancer and the two hybrid populations substantiated the in vitro findings by a significantly elevated tumor growth of the hybrid cells. Moreover, both hybrid populations developed various distant organ metastases in a much shorter period of time than the parental breast cancer cells.

Conclusion

Together, these data demonstrate spontaneous development of new tumor cell populations exhibiting different parental properties after close interaction and subsequent fusion of MSC with breast cancer cells. This formation of tumor hybrids contributes to continuously increasing tumor heterogeneity and elevated metastatic capacities.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0215-4) contains supplementary material, which is available to authorized users.

The cardiotomy reservoir - a preliminary evaluation of a new cell source for cardiovascular tissue engineering

OBJECTIVES

Cell sources for cardiovascular tissue engineering (TE) are scant. However, the need for an ideal TE cardiovascular implant persists. We investigated the cardiotomy reservoir (CR) as a potential cell source that is more accessible and less ethically problematic.

METHODS

CR (n = 10) were removed from the bypass system after surgery. Isolation was performed using different isolation methods: blood samples were taken from the cardiopulmonary bypass and centrifuged at low density. The venous filter screen was cut out and placed into petri dishes for cultivation. The spongelike filter was removed, washed and treated in the same way as the blood samples. After cultivation, cell lines of fibroblasts (FB) and endothelial cells (EC) were obtained for analysis. The cells were seeded on polyurethane patches and analyzed via scanning electron microscopy (SEM), Life/Dead assay and immunohistochemistry.

RESULTS

No correlation between age, time of surgery and quality of cells was observed. The successful extraction of FB and was proven by positive staining results for TE-7, CD31 and vWF. Cell morphology, cytoskeleton staining and quantification of proliferation using WST-1 assay resembled the cells of the control group in all ways. The topography of a confluent and vital cell layer after cell seeding was displayed by SEM analysis, Life/Dead Assay and immunohistochemistry. The establishment of an extracellular matrix (ECM) was proven by positive staining for collagen IV, laminin, fibronectin and elastin.

CONCLUSIONS

Viable FB and EC cell lines were extracted from the CR after surgery. Easy access and high availability make this cell source destined for widespread application in cardiovascular tissue engineering.

Serum-free human MSC medium supports consistency in human but not in equine adipose-derived multipotent mesenchymal stromal cell culture

For clinical applications of multipotent mesenchymal stromal cells (MSCs), serum-free culture is preferable to standardize cell products and prevent contamination with pathogens. In contrast to human MSCs, knowledge on serum-free culture of large animal MSCs is limited, despite its relevance for preclinical studies and development of veterinary cellular therapeutics. This study aimed to evaluate the suitability of a commercially available serum-free human MSC medium for culturing equine adipose-derived MSCs in comparison with human adipose MSCs. Enzyme-free isolation by explant technique and expansion of equine and human cells in the serum-free medium were feasible. However, serum-free culture altered the morphology and complicated handling of equine MSCs, with cell aggregation and spontaneous detachment of multilayers, compared to culture in standard medium supplemented with fetal bovine serum. Furthermore, proliferation and the surface immunophenotype of equine cells were more variable compared to the controls and appeared to depend on the lot of the serum-free medium. Particularly the expression of CD90 was different between experimental groups (P < 0.05), with lower percentages of CD90⁺ cells found in equine MSC samples cultured in serum-free medium (5.21-83.40%) compared to standard medium (86.20-99.50%). Additionally, small subpopulations expressing MSC exclusion markers such as CD14 (0.28-11.60%), CD34 (0.00-9.87%), CD45 (0.35-10.50%), or MHCII (0.00-3.67%) were found in equine samples after serum-free culture. In contrast, human samples displayed a more consistent morphology and a consistent CD29⁺ (98.60-99.90%), CD73⁺ (94.60-98.40%), CD90⁺ (99.60-99.90%), and CD105⁺ (97.40-99.80%) immunophenotype after culture in serum-free medium. The obtained data demonstrate that the serum-free medium was suitable for human MSC culture but did not lead to entirely satisfactory results in equine MSCs. This underlines that requirements regarding serum-free culture conditions are species-specific, indicating a need for serum-free media to be optimized for MSCs from relevant animal species. © 2017 International Society for Advancement of Cytometry.

Stem cell therapies in age-related neurodegenerative diseases and stroke

Aging, a complex process associated with various structural, functional and metabolic changes in the brain, is an important risk factor for neurodegenerative diseases and stroke. These diseases share similar neuropathological changes, such as the formation of misfolded proteins, oxidative stress, loss of neurons and synapses, dysfunction of the neurovascular unit (NVU), reduction of self-repair capacity, and motor and/or cognitive deficiencies. In addition to gray matter dysfunction, the plasticity and repair capacity of white matter also decrease with aging and contribute to neurodegenerative diseases. Aging not only renders patients more susceptible to these disorders, but also attenuates their self-repair capabilities. In addition, low drug responsiveness and intolerable side effects are major challenges in the prevention and treatment of senile diseases. Thus, stem cell therapies-characterized by cellular plasticity and the ability to self-renew-may be a promising strategy for aging-related brain disorders. Here, we review the common pathophysiological changes, treatments, and the promises and limitations of stem cell therapies in age-related neurodegenerative diseases and stroke.

Uncertainty budgeting in fold change determination and implications for non-targeted metabolomics studies in model systems

Uncertainty budgeting provides error intervals for fold change values and complements significance testing in non-targeted metabolomics.

Stem cell therapies for ischemic stroke: current animal models, clinical trials and biomaterials

We report the facilitation of stem cell therapy in stroke by tissue engineering and applications of biomaterials.

Microfluidic systems for stem cell-based neural tissue engineering

Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise control over the spatiotemporal distribution of chemical and physical cues at the cellular level compared to traditional systems. Various microsystems have been designed and fabricated for the purpose of neural tissue engineering. Enhanced neural migration and differentiation, and monitoring of these processes, as well as understanding the behavior of stem cells and their microenvironment have been obtained through application of different microfluidic-based stem cell culture and tissue engineering techniques. As the technology advances it may be possible to construct a "brain-on-a-chip". In this review, we describe the basics of stem cells and tissue engineering as well as microfluidics-based tissue engineering approaches. We review recent testing of various microfluidic approaches for stem cell-based neural tissue engineering.

Relative Effects of Fluid Oscillations and Nutrient Transport in the In Vitro Growth of Valvular Tissues

Engineered valvular tissues are cultured dynamically, and involve specimen movement. We previously demonstrated that oscillatory shear stresses (OSS) under combined steady flow and specimen cyclic flexure (flex-flow) promote tissue formation. However, localized efficiency of specimen mass transport is also important in the context of cell viability within the growing tissues. Here, we investigated the delivery of two essential species for cell survival, glucose and oxygen, to 3-dimensional (3D) engineered valvular tissues. We applied a convective-diffusive model to characterize glucose and oxygen mass transport with and without valve-like specimen flexural movement. We found the mass transport effects for glucose and oxygen to be negligible for scaffold porosities typically present during in vitro experiments and non-essential unless the porosity was unusually low (<40%). For more typical scaffold porosities (75%) however, we found negligible variation in the specimen mass fraction of glucose and oxygen in both non-moving and moving constructs (p > 0.05). Based on this result, we conducted an experiment using bone marrow stem cell (BMSC)-seeded scaffolds under Pulsatile flow-alone states to permit OSS without any specimen movement. BMSC-seeded specimen collagen from the pulsatile flow and flex-flow environments were subsequently found to be comparable (p > 0.05) and exhibited some gene expression similarities. We conclude that a critical magnitude of fluid-induced, OSS created by either pulsatile flow or flex-flow conditions, particularly when the oscillations are physiologically-relevant, is the direct, principal stimulus that promotes engineered valvular tissues and its phenotype, whereas mass transport benefits derived from specimen movement are minimal.

Comparative Analysis of Human Mesenchymal Stem Cells from Umbilical Cord, Dental Pulp, and Menstrual Blood as Sources for Cell Therapy

Although mesenchymal stem cells (MSCs) based therapy has been considered as a promising tool for tissue repair and regeneration, the optimal cell source remains unknown. Umbilical cord (UC), dental pulp (DP), and menstrual blood (MB) are easily accessible sources, which make them attractive candidates for MSCs. The goal of this study was to compare the biological characteristics, including morphology, proliferation, antiapoptosis, multilineage differentiation capacity, and immunophenotype of UC-, DP-, and MB-MSCs in order to provide a theoretical basis for clinical selection and application of these cells. As a result, all UC-, DP-, and MB-MSCs have self-renewal capacity and multipotentiality. However, the UC-MSCs seemed to have higher cell proliferation ability, while DP-MSCs may have significant advantages for osteogenic differentiation, lower cell apoptosis, and senescence. These differences may be associated with the different expression level of cytokines, including vascular endothelial growth factor, fibroblast growth factor, keratinocyte growth factor, and hepatocyte growth factor in each of the MSCs. Comprehensively, our results suggest DP-MSCs may be a desired source for clinical applications of cell therapy.

Fabrication of tissue-engineered vascular grafts with stem cells and stem cell-derived vascular cells

INTRODUCTION

Cardiovascular disease is the leading cause of mortality worldwide. Current surgical treatments for cardiovascular disease include vascular bypass grafting and replacement with autologous blood vessels or synthetic vascular grafts. However, there is a call for better alternative biological grafts.

AREAS COVERED

Tissue-engineered vascular grafts (TEVGs) are promising novel alternatives to replace diseased vessels. However, obtaining enough functional and clinically usable vascular cells for fabrication of TEVGs remains a major challenge. New findings in adult stem cells and recent advances in pluripotent stem cells have opened a new avenue for stem cell-based vascular engineering. In this review, recent advances on stem cell sourcing for TEVGs including the use of adult stem cells and pluripotent stem cells and advantages, disadvantages, and possible future implementations of different types of stem cells will be discussed. In addition, current strategies used during the fabrication of TEVGs will be highlighted.

EXPERT OPINION

The application of patient-specific TEVGs constructed with vascular cells derived from immune-compatible stem cells possesses huge clinical potential. Advances in lineage-specific differentiation approaches and innovative vascular engineering strategies will promote the vascular regeneration field from bench to bedside.

Human plasma and human platelet-rich plasma as a substitute for fetal calf serum during long-term cultivation of mesenchymal dental pulp stem cells

AIMS

Our aims were to isolate and cultivate mesenchymal dental pulp stem cells (DPSC) in various media enriched with human blood components, and subsequently to investigate their basic biological properties.

METHODS

DPSC were cultivated in five different media based on α MEM containing different concentrations of human plasma (HP), platelet-rich plasma (PRP), or fetal calf serum (FCS). The DPSC biological properties were examined periodically.

RESULTS

We cultivated DPSC in the various cultivation media over 15 population doublings except for the medium supplemented with 10% HP. Our results showed that DPSC cultivated in medium supplemented with 10% PRP showed the shortest average population doubling time (DT) (28.6 ± 4.6 hours), in contrast to DPSC cultivated in 10% HP which indicated the longest DT (156.2 ± 17.8 hours); hence this part of the experiment had been cancelled in the 6th passage. DPSC cultivated in media with 2% FCS+ITS (DT 47.3 ± 10.4 hours), 2% PRP (DT 40.1 ± 5.7 hours) and 2% HP (DT 49.0 ± 15.2 hours) showed almost the same proliferative activity. DPSC's viability in the 9th passage was over 90% except for the DPSC cultivated in the 10% HP media.

CONCLUSIONS

We proved that human blood components are suitable substitution for FCS in cultivation media for long-term DPSC cultivation.

Osteogenic differentiation of amniotic fluid mesenchymal stromal cells and their bone regeneration potential

In orthopedics, tissue engineering approach using stem cells is a valid line of treatment for patients with bone defects. In this context, mesenchymal stromal cells of various origins have been extensively studied and continue to be a matter of debate. Although mesenchymal stromal cells from bone marrow are already clinically applied, recent evidence suggests that one may use mesenchymal stromal cells from extra-embryonic tissues, such as amniotic fluid, as an innovative and advantageous resource for bone regeneration. The use of cells from amniotic fluid does not raise ethical problems and provides a sufficient number of cells without invasive procedures. Furthermore, they do not develop into teratomas when transplanted, a consequence observed with pluripotent stem cells. In addition, their multipotent differentiation ability, low immunogenicity, and anti-inflammatory properties make them ideal candidates for bone regenerative medicine. We here present an overview of the features of amniotic fluid mesenchymal stromal cells and their potential in the osteogenic differentiation process. We have examined the papers actually available on this regard, with particular interest in the strategies applied to improve in vitro osteogenesis. Importantly, a detailed understanding of the behavior of amniotic fluid mesenchymal stromal cells and their osteogenic ability is desirable considering a feasible application in bone regenerative medicine.

Wharton's Jelly-Derived Mesenchymal Stromal Cells as a Promising Cellular Therapeutic Strategy for the Management of Graft-versus-Host Disease

Allogeneic hematopoietic cell transplantation (allo-HCT), a treatment option in hematologic malignancies and bone marrow failure syndromes, is frequently complicated by Graft-versus-host disease (GVHD). The primary treatment for GVHD involves immune suppression by glucocorticoids. However, patients are often refractory to the steroid therapy, and this results in a poor prognosis. Therefore alternative therapies are needed to treat GVHD. Here, we review data supporting the clinical investigation of a novel cellular therapy using Wharton’s jelly (WJ)-derived mesenchymal stromal cells (MSCs) as a potentially safe and effective therapeutic strategy in the management of GVHD. Adult-derived sources of MSCs have demonstrated signals of efficacy in the management of GVHD. However, there are limitations, including: limited proliferation capacity; heterogeneity of cell sources; lengthy expansion time to clinical dose; expansion failure in vitro; and a painful, invasive, isolation procedure for the donor. Therefore, alternative MSC sources for cellular therapy are sought. The reviewed data suggests MSCs derived from WJ may be a safe and effective cellular therapy for GVHD. Laboratories investigated and defined the immune properties of WJ-MSCs for potential use in cellular therapy. These cells represent a more uniform cell population than bone marrow-derived MSCs, displaying robust immunosuppressive properties and lacking significant immunogenicity. They can be collected safely and painlessly from individuals at birth, rapidly expanded and stored cryogenically for later clinical use. Additionally, data we reviewed suggested licensing MSCs (activating MSCs by exposure to cytokines) to enhance effectiveness in treating GVHD. Therefore, WJCs should be tested as a second generation, relatively homogeneous allogeneic cell therapy for the treatment of GVHD.

Tissue engineering strategies to study cartilage development, degeneration and regeneration

Cartilage tissue engineering has primarily focused on the generation of grafts to repair cartilage defects due to traumatic injury and disease. However engineered cartilage tissues have also a strong scientific value as advanced 3D culture models. Here we first describe key aspects of embryonic chondrogenesis and possible cell sources/culture systems for in vitro cartilage generation. We then review how a tissue engineering approach has been and could be further exploited to investigate different aspects of cartilage development and degeneration. The generated knowledge is expected to inform new cartilage regeneration strategies, beyond a classical tissue engineering paradigm.

The potential use of mesenchymal stem cells in stroke therapy--From bench to bedside

Stroke is the second main cause of morbidity and mortality worldwide. The rationale for the use of mesenchymal stem cells (MSCs) in stroke is based on the capacity of MSCs to secrete a large variety of bioactive molecules such as growth factors, cytokines and chemokines leading to reduction of inflammation, increased neurogenesis from the germinative niches of central nervous system, increased angiogenesis, effects on astrocytes, oligodendrocytes and axons. This review presents the data derived from experimental studies and the evidence available from clinical trials about the use of MSCs in stroke therapy.

Electrophysiological functional recovery in a rat model of spinal cord hemisection injury following bone marrow-derived mesenchymal stem cell transplantation under hypothermia

Following successful establishment of a rat model of spinal cord hemisection injury by resecting right spinal cord tissues, bone marrow stem cells were transplanted into the spinal cord lesions via the caudal vein while maintaining rectal temperature at 34 ± 0.5°C for 6 hours (mild hypothermia). Hematoxylin-eosin staining showed that astrocytes gathered around the injury site and formed scars at 4 weeks post-transplantation. Compared with rats transplanted with bone marrow stem cells under normal temperature, rats transplanted with bone marrow stem cells under hypothermia showed increased numbers of proliferating cells (bromodeoxyuridine-positive cells), better recovery of somatosensory-evoked and motor-evoked potentials, greater Basso, Beattie, and Bresnahan locomotor rating scores, and an increased degree of angle in the incline plate test. These findings suggested that hypothermia combined with bone marrow mesenchymal stem cells transplantation effectively promoted electrical conduction and nerve functional repair in a rat model of spinal cord hemisection injury.

The osteogenic properties of multipotent mesenchymal stromal cells in cultures on TiO₂ sol-gel-derived biomaterial

The biocompatibility of the bone implants is a crucial factor determining the successful tissue regeneration. The aim of this work was to compare cellular behavior and osteogenic properties of rat adipose-derived multipotent stromal cells (ASCs) and bone marrow multipotent stromal cells (BMSCs) cultured on metallic substrate covered with TiO2 sol-gel-derived nanolayer. The morphology, proliferation rate, and osteogenic differentiation potential of both ASCs and BMSCs propagated on the biomaterials were examined. The potential for osteogenic differentiation of ASCs and BMSCs was determined based on the presence of specific markers of osteogenesis, that is, alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCL). Additionally, the concentration of calcium and phosphorus in extracellular matrix was determined using energy-dispersive X-ray spectroscopy (SEM-EDX). Obtained results showed that TiO2 layer influenced proliferation activity of ASCs, which manifested by shortening of population doubling time and increase of OPN secretion. However, characteristic features of cells morphology and growth pattern of cultures prompted us to conclude that ultrathin TiO2 layer might also enhance osteodifferentiation of BMSCs. Therefore in our opinion, both populations of MSCs should be used for biological evaluation of biomaterials compatibility, such results may enhance the area of investigations related to regenerative medicine.

Stem cell therapy in neurodegenerative diseases: From principles to practice

The lack of curative therapies for neurodegenerative diseases has high economic impact and places huge burden on the society. The contribution of stem cells to cure neurodegenerative diseases has been unraveled and explored extensively over the past few years. Beyond substitution of the lost neurons, stem cells act as immunomodulators and neuroprotectors. A large number of preclinical and a small number of clinical studies have shown beneficial outcomes in this context. In this review, we have summarized the current concepts of stem cell therapy in neurodegenerative diseases and the recent advances in this field, particularly between 2010 and 2012. Further studies should be encouraged to resolve the clinical issues and vague translational findings for maximum optimization of the efficacy of stem cell therapy in neurodegenerative diseases.

Management of hyperhidrosis

Primary hyperhidrosis (HH), a condition of sweating in excess of thermoregulatory requirements, affects nearly 3% of the US population and carries significant emotional and psychosocial implications. Unlike secondary HH, primary HH is not associated with an identifiable underlying pathology. Our limited understanding of the precise pathophysiologic mechanism for HH makes its treatment particularly frustrating. However, a wide array of interventions for the treatment of HH have been implemented throughout the world. Herein, we discuss the most extensively studied therapeutic options for primary HH, including systemic oxybutynin, botulinum toxin injections, skin excision, liposuction–curettage, and sympathotomy/sympathectomy. We conclude with a discussion of possible future therapies for HH, including the applications of laser, microwave, and ultrasound technologies.

Single cell sorting identifies progenitor cell population from full thickness bovine articular cartilage

OBJECTIVE

To date, no approved clinical intervention successfully prevents the progressive degradation of injured articular cartilage that leads to osteoarthritis (OA). Stem/progenitor cell populations within tissues of diarthrodial joint have shown their therapeutic potential in treating OA. However, this potential has not been fully realized due in part to the heterogeneity of these subpopulations. Characterization of clonal populations derived from a single cell may help identify more homogenous stem/progenitor populations within articular cartilage. Moreover, chondrogenic potential of clonal populations from different zones could be further examined to elucidate their differential roles in maintaining articular cartilage homeostasis.

METHOD

We combined Fluorescence-activated cell sorting (FACS) and clonogenicity screening to identify stem/progenitor cells cloned from single cells. High-efficiency colony-forming cells (HCCs) were isolated, and evaluated for stem/progenitor cell characteristics. HCCs were also isolated from different zones of articular cartilage. Their function was compared by lineage-specific gene expression, and differentiation potential.

RESULTS

A difference in colony-forming efficiency was observed in terms of colony sizes. HCCs were highly clonogenic and multipotent, and overexpressed stem/progenitor cell markers. Also, proliferation and migration associated genes were over-expressed in HCCs. HCCs showed zonal differences with deep HCCs more chondrogenic and osteogenic than superficial HCCs.

CONCLUSION

Our approach is a simple yet practical way to identify homogeneous stem/progenitor cell populations with clonal origin. The discovery of progenitor cells demonstrates the intrinsic self-repairing potential of articular cartilage. Differences in differentiation potential may represent the distinct roles of superficial and deep zone stem/progenitor cells in the maintenance of articular cartilage homeostasis.

Biomaterials in myocardial tissue engineering

Cardiovascular disease is the leading cause of death in the developed world, and as such there is a pressing need for treatment options. Cardiac tissue engineering emerged from the need to develop alternative sources and methods of replacing tissue damaged by cardiovascular diseases, as the ultimate treatment option for many who suffer from end-stage heart failure is a heart transplant. In this review we focus on biomaterial approaches to augmenting injured or impaired myocardium, with specific emphasis on: the design criteria for these biomaterials; the types of scaffolds - composed of natural or synthetic biomaterials or decellularized extracellular matrix - that have been used to develop cardiac patches and tissue models; methods to vascularize scaffolds and engineered tissue; and finally, injectable biomaterials (hydrogels) designed for endogenous repair, exogenous repair or as bulking agents to maintain ventricular geometry post-infarct. The challenges facing the field and obstacles that must be overcome to develop truly clinically viable cardiac therapies are also discussed.

The effect of fetal calf serum on human dental pulp stem cells

AIMS

Authors studied potential side effects of fetal calf serum (FCS) in cultivation media on human dental pulp stem cells (DPSC) during long-term cultivation.

METHODS

Two lines of DPSC obtained healthy donors (male 22 years, female 23 years) were used. Both lines were cultivated under standard cultivation conditions in four different media containing 10% or 2% FCS and substituted with growth factors. During long-term cultivation proliferation ability, karyotype and phenotype of DPSC were measured.

RESULTS

Both lines of DPSC cultivated in a media containing 2% FCS and ITS supplement showed the highest number of population doublings. On the other hand the proliferation rate of DPSC cultivated in a media with 2% FCS without ITS supplement was slowest. Proliferation rate of DPSC cultivated in 10% FCS media with or without FGF-2 was comparable. DPSC cultivated in a media with 10% FCS showed a significantly higher amount of chromosomal aberrations. These chromosomal aberrations do not seem to be clonal but surprisingly we found large amounts of tetraploid cells in the 9th passage in both media containing 10% FCS.

CONCLUSIONS

Our study proved that cultivation of DPSC in media containing higher concentration of FCS has critical side effects on cell chromosomal stability.