Choosing the right type of serum for different applications of human adipose tissue-derived stem cells: influence on proliferation and differentiation abilities

A novel cell source for therapy of knee osteoarthritis using atelocollagen microsphere-adhered adipose-derived stem cells: Impact of synovial fluid exposure on cell activity

Introduction

Administration of adipose-derived stem cells (ADSCs) into the joint cavity has been shown to alleviate the symptoms of knee osteoarthritis (OA) by releasing exosomes and anti-inflammatory cytokines. However, the therapeutic effect of these cells is limited by their rapid disappearance after administration. Thus, it is necessary to prolong cell survival in the joint cavity. This study aimed to investigate the potential application of ADSCs adhered to atelocollagen microspheres (AMSs) for cell therapy of knee OA.

Methods

ADSCs were cultured for 2, 4, and 7 days in AMS suspension or adherent culture dishes. The supernatants were analyzed for IL-10 and exosome secretion via enzyme-linked immunosorbent assay and Nanosight. The effect of AMS was compared with that of adherent-cultured ADSCs (2D-cultured ADSCs) using transcriptome analysis. Moreover, the solubility of AMS and viability of ADSCs were evaluated using synovial fluid (SF) from patients with knee OA.

Results

Compared with 2D-cultured ADSCs, AMS-cultured ADSCs exhibited a significant increase in secretion of exosomes and IL-10, and the expression of several genes involved in extracellular matrix and immune regulation were altered. Furthermore, when AMS-cultured ADSCs were cultured in SF from knee OA patients to mimic the intra-articular environment, the SF dissolved the AMSs and released viable ADSCs. In addition, AMS-cultured ADSCs showed significantly higher long-term cell viability than 2D-cultured ADSCs.

Conclusion

Increased survival of AMS-adhered ADSCs was observed in the intra-articular environment, and AMSs were found to gradually dissipate. These results suggest that AMS-adhered ADSCs are promising source for cell therapy of knee OA.

Better isolation, proliferation and differentiation of human adipose-derived mesenchymal stem cells using human serum

Mesenchymal stem cells have many applications in medicine. Attention to the proliferation and differentiation of stem cell differentiation is an important issue. The aim of this study was to investigate the possibility of optimal isolation, proliferation, and differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) using human serum. Human serum (HS) was obtained from the venous blood of eight healthy individuals. The rate of proliferation and differentiation of ADSCs and expression of surface markers was assessed by flow cytometry. Bone differentiation was assessed using Alizarin Red staining. Data were analyzed using statistical software. Over time, HS showed more proliferation than fetal bovine serum (FBS) -enriched cells (p <0.05). Differentiation of ADSCs cells ls in HS-enriched medium is faster and more pronounced than differentiation in the control group. The expression of surface markers in the medium containing HS was the same as the medium containing FBS where the expression levels of CD105 and CD95 were found to be positive and the expression of CD34 and CD45 was negative. Due to the better proliferation of adipose tissue-derived mesenchymal cells in the medium containing HS than FBS, it is suggested that human serum be used in future clinical studies. Also, HS is healthier, safer, more accessible, and more affordable than FBS.

Synovial Fluid Derived from Human Knee Osteoarthritis Increases the Viability of Human Adipose-Derived Stem Cells through Upregulation of FOSL1

Knee osteoarthritis (Knee OA) is an irreversible condition that causes bone deformity and degeneration of the articular cartilage that comprises the joints, resulting in chronic pain and movement disorders. The administration of cultured adipose-derived stem cells (ADSCs) into the knee joint cavity improves the clinical symptoms of Knee OA; however, the effect of synovial fluid (SF) filling the joint cavity on the injected ADSCs remains unclear. In this study, we investigated the effect of adding SF from Knee OA patients to cultured ADSCs prepared for therapeutic use in an environment that mimics the joint cavity. An increase in the viability of ADSCs was observed following the addition of SF. Gene expression profiling of SF-treated ADSCs using DNA microarrays revealed changes in several genes involved in cell survival. Of these genes, we focused on FOSL1, which is involved in the therapeutic effect of ADSCs and the survival and proliferation of cancer stem cells. We confirmed the upregulation of FOSL1 mRNA and protein expression using RT-PCR and western blot analysis, respectively. Next, we knocked down FOSL1 in ADSCs using siRNA and observed a decrease in cell viability, indicating the involvement of FOSL1 in the survival of ADSCs. Interestingly, in the knockdown cells, ADSC viability was also decreased by SF exposure. These results suggest that SF enhances cell viability by upregulating FOSL1 expression in ADSCs. For therapy using cultured ADSCs, the therapeutic effect of ADSCs may be further enhanced if an environment more conducive to the upregulation of FOSL1 expression in ADSCs can be established.

Therapeutic potential of small extracellular vesicles derived from mesenchymal stem cells for spinal cord and nerve injury

Neural diseases such as compressive, congenital, and traumatic injuries have diverse consequences, from benign mild sequelae to severe life-threatening conditions with associated losses of motor, sensory, and autonomic functions. Several approaches have been adopted to control neuroinflammatory cascades. Traditionally, mesenchymal stem cells (MSCs) have been regarded as therapeutic agents, as they possess growth factors and cytokines with potential anti-inflammatory and regenerative effects. However, several animal model studies have reported conflicting outcomes, and therefore, the role of MSCs as a regenerative source for the treatment of neural pathologies remains debatable. In addition, issues such as heterogeneity and ethical issues limited their use as therapeutic agents. To overcome the obstacles associated with the use of traditional agents, we explored the therapeutic potentials of extracellular vesicles (EVs), which contain nucleic acids, functional proteins, and bioactive lipids, and play crucial roles in immune response regulation, inflammation reduction, and cell-to-cell communication. EVs may surpass MSCs in size issue, immunogenicity, and response to the host environment. However, a comprehensive review is required on the therapeutic potential of EVs for the treatment of neural pathologies. In this review, we discuss the action mechanism of EVs, their potential for treating neural pathologies, and future perspectives regarding their clinical applications.

Different levels of EGF, VEGF, IL-6, MCP-1, MCP-3, IP-10, Eotaxin and MIP-1α in the adipose-derived stem cell secretome in androgenetic alopecia

Hair folliculogenesis and hair growth mediated by the secretory properties of white adipocytes may pave the way for the adipose-derived (AD) regenerative therapy for androgenetic alopecia (AGA). Quantitative and qualitative secretome profiling of AD stem cells (ADSCs) from different zones of hair growth in patients with AGA were analysed. 1mm punch samples of adipose tissue associated with hair follicles, of three scalp areas (balding, non-balding and transition zone) and one periumbilical sample, were used for ADCS isolation. The ADCS secretome was analysed in conditioned media using a 41plex assay. Among the thirty-five signalling proteins analysed, the levels of VEGF, EGF, IL-6, Eotaxin, MCP-3, IFNγ-inducible Protein-10 and MIP-1α were higher in the balding zone compared with the non-balding and periumbilical zones. In contrast, MCP-1 was lowest in the balding zone in comparison to the other zones. The observed differences in the secretome suggest crosstalk between angiogenic and inflammatory processes underlying AGA etiology and may prove relevant in both the diagnosis of AGA and the application of ADSC secretome for AGA treatment.

The effect of medium supplementation and serial passaging on the transcriptome of human adipose-derived stromal cells expanded in vitro

BACKGROUND

For adipose-derived stromal cells (ASCs) to be safe for use in the clinical setting, they need to be prepared using good manufacturing practices (GMPs). Fetal bovine serum (FBS), used to expand ASCs in vitro in some human clinical trials, runs the risk of xenoimmunization and zoonotic disease transmission. To ensure that GMP standards are maintained, pooled human platelet lysate (pHPL) has been used as an alternative to FBS. ASCs proliferate more rapidly in pHPL than in FBS, with no significant change in immunophenotype and differentiation capacity. However, not much is known about how pHPL affects the transcriptome of these cells.

METHODS

This study investigated the effect of pHPL and FBS on the ASC transcriptome during in vitro serial expansion from passage 0 to passage 5 (P0 to P5). RNA was isolated from ASCs at each passage and hybridized to Affymetrix HuGene 2.0 ST arrays for gene expression analysis.

RESULTS

We observed that the transcriptome of ASCs expanded in pHPL (pHPL-ASCs) and FBS (FBS-ASCs) had the greatest change in gene expression at P2. Gene ontology revealed that genes upregulated in pHPL-ASCs were enriched for cell cycle, migration, motility, and cell-cell interaction processes, while those in FBS-ASCs were enriched for immune response processes. ASC transcriptomes were most homogenous from P2 to P5 in FBS and from P3 to P5 in pHPL. FBS- and pHPL-gene-specific signatures were observed, which could be used as markers to identify cells previously grown in either FBS or pHPL for downstream clinical/research applications. The number of genes constituting the FBS-specific effect was 3 times greater than for pHPL, suggesting that pHPL may be a milder supplement for cell expansion. A set of genes were expressed in ASCs at all passages and in both media. This suggests that a unique ASC in vitro transcriptomic profile exists that is independent of the passage number or medium used.

CONCLUSIONS

GO classification revealed that pHPL-ASCs are more involved in cell cycle processes and cellular proliferation when compared to FBS-ASCs, which are involved in more specialized or differentiation processes like cardiovascular and vascular development. This makes pHPL a potential superior supplement for expanding ASCs as they retain their proliferative capacity, remain untransformed and pHPL does not affect the genes involved in differentiation in specific developmental processes.

Reference Gene Expression in Adipose-Derived Stromal Cells Undergoing Adipogenic Differentiation

IMPACT STATEMENT

As the use of adipose-derived stromal cells (ASCs) in clinical trials increases, so does the amount of experimental data from research groups, many of which use human ASCs to study adipogenesis in obesity. Different conditions are constantly being applied to ASCs in vitro, to obtain a therapeutic product for potential downstream applications. Few articles have looked at the effect of different conditions on ASC reference gene (RG) expression and stability, which was the aim of this research, as such this article will assist other researchers to make an informed decision about RG selection for gene expression studies using ASCs including those for adipogenesis.

Perspectives for Clinical Translation of Adipose Stromal/Stem Cells

Adipose stromal/stem cells (ASCs) are an ideal cell type for regenerative medicine applications, as they can easily be harvested from adipose tissue in large quantities. ASCs have excellent proliferation, differentiation, and immunoregulatory capacities that have been demonstrated in numerous studies. Great interest and investment have been placed in efforts to exploit the allogeneic use and immunomodulatory and anti-inflammatory effects of ASCs. However, bridging the gap between in vitro and in vivo studies and moving into clinical practice remain a challenge. For the clinical translation of ASCs, several issues must be considered, including how to characterise such a heterogenic cell population and how to ensure their safety and efficacy. This review explores the different phases of in vitro and preclinical ASC characterisation and describes the development of appropriate potency assays. In addition, good manufacturing practice requirements are discussed, and cell-based medicinal products holding marketing authorisation in the European Union are reviewed. Moreover, the current status of clinical trials applying ASCs and the patent landscape in the field of ASC research are presented. Overall, this review highlights the applicability of ASCs for clinical cell therapies and discusses their potential.

Impact of Human Adipose Tissue-Derived Stem Cells on Malignant Melanoma Cells in An In Vitro Co-culture Model

This study focuses on the interactions of human adipose tissue-derived stem cells (ADSCs) and malignant melanoma cells (MMCs) with regard to future cell-based skin therapies. The aim was to identify potential oncological risks as ADSCs could unintentionally be sited within the proximity of the tumor microenvironment of MMCs. An indirect co-culture model was used to analyze interactions between ADSCs and four different established melanoma cell lines (G-361, SK-Mel-5, MeWo and A2058) as well as two low-passage primary melanoma cell cultures (M1 and M2). Doubling time, migration and invasion, angiogenesis, quantitative real-time PCR of 229 tumor-associated genes and multiplex protein assays of 20 chemokines and growth factors and eight matrix metalloproteinases (MMPs) were evaluated. Co-culture with ADSCs significantly increased migration capacity of G-361, SK-Mel-5, A2058, MeWo and M1 and invasion capacity of G-361, SK-Mel-5 and A2058 melanoma cells. Furthermore, conditioned media from all ADSC-MMC-co-cultures induced tube formation in an angiogenesis assay in vitro. Gene expression analysis of ADSCs and MMCs, especially of low-passage melanoma cell cultures, revealed an increased expression of various genes with tumor-promoting activities, such as CXCL12, PTGS2, IL-6, and HGF upon ADSC-MMC-co-culture. In this context, a significant increase (up to 5,145-fold) in the expression of numerous tumor-associated proteins could be observed, e.g. several pro-angiogenic factors, such as VEGF, IL-8, and CCL2, as well as different matrix metalloproteinases, especially MMP-2. In conclusion, the current report clearly demonstrates that a bi-directional crosstalk between ADSCs and melanoma cells can enhance different malignant properties of melanoma cells in vitro.

In Vitro Expression of Cytokeratin 19 in Adipose-Derived Stem Cells Is Induced by Epidermal Growth Factor

BACKGROUND Cytokeratin 19 (CK19) is a typical epithelial marker. In this study, we determined whether epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF) could enhance CK19 expression in adipose-derived stem cells (ADSCs), thereby inducing the differentiation of ADSCs into epithelial-like cells. MATERIAL AND METHODS ADSCs were isolated from perinephric fat, and the expression of CD29, CD90, and CD105 was confirmed. Following isolation, ADSCs were cultured in static medium or medium containing EGF or bFGF. RESULTS Flow cytometry revealed that EGF and bFGF could alter mesenchymal stem cell markers as well as the cell cycle of ADSCs. Western blotting and immunofluorescence revealed that after 14 days, EGF treatment enhanced the expression of CK19 in ADSCs. CONCLUSIONS Our findings offer important insight for the clinical use of ADSCs in the generation of epithelial-like cells in the future.

Adipose-Derived Mesenchymal Stem Cells in the Use of Cartilage Tissue Engineering: The Need for a Rapid Isolation Procedure

Mesenchymal stem cells (MSCs) have shown much promise with respect to their use in cartilage tissue engineering. MSCs can be obtained from many different tissue sources. Among these, adipose tissue can provide an abundant source of adipose-derived mesenchymal stem cells (ADMSCs). The infrapatellar fat pad (IFP) is a promising source of ADMSCs with respect to producing a cartilage lineage. Cell isolation protocols to date are time-consuming and follow conservative approaches that rely on a long incubation period of 24–48 hours. The different types of ADMSC isolation techniques used for cartilage repair will be reviewed and compared with the view of developing a rapid one-step isolation protocol that can be applied in the context of a surgical procedure.

Comparison of human platelet lysate alternatives using expired and freshly isolated platelet concentrates for adipose-derived stromal cell expansion

Pooled human platelet lysate (pHPL) has been used to expand adipose-derived stromal cells (ASCs) and can be formulated using fresh or expired buffy coats (BCs) which are then resuspended in either plasma or an additive solution. Not much is known about the effects that expired products and additive solutions have on ASC expansion, and the need for quality control and release criteria has been expressed. This pilot study compared proliferation, cell size, morphology and immunophenotype of ASCs expanded in the different pHPL alternatives versus foetal bovine serum (FBS). Quality control criteria were assessed prior to and during the manufacture of the pHPL alternatives. ASCs were then expanded in 1%, 2.5%, 5% or 10% of the different pHPL alternatives or in 10% FBS. Cell size, morphology, cell number and immunophenotype were measured using microscopy and flow cytometry. The majority of the pHPL alternatives were within the recommended ranges for the quality control criteria. ASCs expanded in the pHPL alternatives were smaller in size, displayed a tighter spindle-shaped morphology, increased cell growth and had a similar immunophenotype (with the exception of CD34 and CD36) when compared to ASCs expanded in FBS. Here we report on the effects that expired BC products and additive solutions have on ASC expansion. When taken together, our findings indicate that all of the pHPL alternatives can be considered to be suitable replacements for FBS for ASC expansion, and that expired BC products can be used as an alternative to fresh BC products.

The effect of serum types on Chondrogenic differentiation of adipose-derived stem cells

Background

Fetal bovine serum (FBS) is the most essential supplement in culture media for cellular proliferation, metabolism, and differentiation. However, due to a limited supply and subsequently rising prices, a series of studies have investigated a biological feasibility of replaceable serums to substitute FBS. Along with the increasing interests to manufacture stem cell-based cellular products, optimizing the composition of culture media including serums and exogenous growth factors (GFs) is of importance. In this experiment, the effect of bovine serum (BS) and newborn calf serum (NCS) on proliferation and chondrogenic differentiation capacity of human adipose derived stem cells (ADSCs) was evaluated, especially in the chondrogenically supplemented culture condition.

Methods

ADSCs were chondrogenically cultured with FBS, BS, and NCS for 14 days. For the acceleration of in vitro chondrogenesis, exogenous insulin-like growth factor and transforming growth factor-β3 were added. Viability and proliferation of ADSCs were evaluated using Live/Dead fluorescence staining and DNA amount, respectively. To investigate a chondrogenic differentiation, a series of assays were performed including a quantification of glycosaminoglycan deposition, alcian blue staining, and RT-PCR analysis for type II collagen, aggrecan and Sox-9 genes.

Results

The results demonstrated that proliferation of ADSCs was facilitated in FBS condition as compared with other serum types. For chondrogenic marker gene expression, serum substitutes enhanced Sox-9 expression level on day 14. The deposition of glycosaminoglycan was more facilitated in BS condition regardless of additional chondrogenic GFs.

Conclusion

It could be presumably speculated that serum types and exogenous supplements of GFs could also be important parameters to optimize culture media composition, especially in order to maintain the enhanced levels of both proliferation and chondrogenic differentiation of ADSCs during expansion.

The Effects of Hyperacute Serum on Adipogenesis and Cell Proliferation of Mesenchymal Stromal Cells

Fat tissue, due to its high concentration of stem cells, has a role in aesthetic medicine and reconstructive surgery. However, poor survival of the transplanted cells still limits the usefulness of this material in regenerative medicine. Several studies indicated that platelet-rich plasma (PRP) may improve adipose tissue viability due to its growth factor content. This study aimed at investigating the effects of PRP and hyperacute serum (HAS) on the adipogenic lineage in vitro. PRP was prepared by using two centrifugation steps in the presence of anticoagulants, and HAS was isolated from activated platelet-rich fibrin within 10 min of blood drawing to prevent the propagation of inflammatory cascades. Metabolic activity and proliferation rate of human bone marrow-derived mesenchymal stem cells (hMSCs) cultivated in media supplemented with three types of serum additives (fetal calf serum [FCS], human PRP, or HAS) was determined by using a tetrazolium assay. Adipogenesis was evaluated in standard and pro-adipogenic media and tested by oil red staining, triglyceride content, and expression of specific genes. Adipogenic regulators in the sera were measured by multiplex ELISA assays. We observed that proliferation of hMSCs was supported by both FCS and HAS in a time-dependent manner, but surprisingly, PRP had a much weaker effect (change in proliferation rate after 5 days relative to metabolic activity on day 0-FCS: 5.4-fold change, HAS: 5.8-fold change, serum free 1.9-fold change, PRP: 3.0-fold change, p < 0.05). Lipogenesis was only observed in groups with adipogenic differentiation medium, with HAS showing a significantly stronger effect than PRP. This was confirmed by intensive accumulation of lysochrome dye in lipid droplets, higher triglyceride concentration, and elevated expression of specific adipogenic genes. Measurement of lipogenic proteins in the sera revealed that both PRP and HAS are abundant in them; however, PRP also contains anti-adipogenic factors, which explains its weaker and less reliable effect. The results of this study suggest that HAS provides more robust support than PRP in hMSCs proliferation as well as lipogenic differentiation, indicating that it may be a better adjuvant in fat grafting procedures.

The use of stem cells in aesthetic dermatology and plastic surgery procedures. A compact review of experimental and clinical applications

The aim of this paper was to collect currently available data related to the use of stem cells in aesthetic dermatology and plastic surgery based on a systemic review of experimental and clinical applications. We found that the use of stem cells is very promising but the current state of art is still not effective. This situation is connected with not fully known mechanisms of cell interactions, possible risks and side effects. We think that there is a big need to create and conduct different studies which could resolve problems of stem cells use for implementation into aesthetic dermatology and plastic surgery.

Venous Blood Derivatives as FBS-Substitutes for Mesenchymal Stem Cells: A Systematic Scoping Review

Although the biological properties of mesenchymal stem cells (MSC) are well-characterized in vitro, MSC clinical application is still far away to be achieved, mainly due to the need of xenogeneic substances for cell expansion, such as fetal bovine serum (FBS). FBS presents risks regarding pathogens transmissions and internalization of animal's proteins, which can unleash antigenic responses in patients after MSC implantation. A wide range of venous blood derivatives (VBD) has been reported as FBS substitutes showing promising results. Thus, the aim of this study was to conduct a systematic scoping review to analyze whether VBD are effective FBS substitutes for MSC ex vivo expansion. The search was performed in SciVerse ScopusTM, PubMed, Web of ScienceTM, BIREME, Cochrane library up to January 2016. The keywords were selected using MeSH and entry terms. Two independent reviewers scrutinized the records obtained considering specific inclusion criteria. The included studies were evaluated in accordance with a modified Arksey and O' Malley's framework. From 184 found studies, 90 were included. Bone marrow mesenchymal stem cells (BMMSC) were presented in most of these studies. Overall, VBD allowed for either, maintenance of MCS's fibroblast-like morphology, high proliferation, high colony-formation ability and maintenance of multipotency. Besides. MSC expanded in VBD supplements presented higher mitogen activity than FBS. VBD seems to be excellent xeno-free serum for ex vivo expansion of mesenchymal stem cells. However, an accentuated heterogeneity was observed between the carried out protocols for VBD isolation did not allowing for direct comparisons between the included studies.

Tissue Source and Cell Expansion Condition Influence Phenotypic Changes of Adipose-Derived Stem Cells

Stem cells derived from the subcutaneous adipose tissue of debrided burned skin represent an appealing source of adipose-derived stem cells (ASCs) for regenerative medicine. Traditional tissue culture uses fetal bovine serum (FBS), which complicates utilization of ASCs in human medicine. Human platelet lysate (hPL) is one potential xeno-free, alternative supplement for use in ASC culture. In this study, adipogenic and osteogenic differentiation in media supplemented with 10% FBS or 10% hPL was compared in human ASCs derived from abdominoplasty (HAP) or from adipose associated with debrided burned skin (BH). Most (95–99%) cells cultured in FBS were stained positive for CD73, CD90, CD105, and CD142. FBS supplementation was associated with increased triglyceride content and expression of adipogenic genes. Culture in hPL significantly decreased surface staining of CD105 by 31% and 48% and CD142 by 27% and 35% in HAP and BH, respectively (p < 0.05). Culture of BH-ASCs in hPL also increased expression of markers of osteogenesis and increased ALP activity. These data indicate that application of ASCs for wound healing may be influenced by ASC source as well as culture conditions used to expand them. As such, these factors must be taken into consideration before ASCs are used for regenerative purposes.

Platelet-Poor Plasma as a Supplement for Fibroblasts Cultured in Platelet-Rich Fibrin

The aim of this study was to evaluate the proliferation and adhesion of mesenchymal cells (3T3/NIH) in Dulbecco’s Modified Eagle Medium(DMEM) supplemented with Platelet-Poor Plasma (PPP) in aPlatelet-Rich Fibrin (PRF) scaffold. Human blood was obtained and processed in a centrifuge considering the equation G=1.12xRx(RPM/1000)² to obtain PRF and PPP.Cell adhesion and maintenance analyses were performed by MTTassays in a 96 well plate withsupplemented DMEM: PPP (90:10) for 24 hours. Besides, the PRF was deposited in a 48 well plate and 10x10⁴ cells were seeded above each PRF (n=3) with 800µl of DMEM: PPP (90:10) and cultured for 7 days. Histological analysis and the immunohistochemical staining for Vimentin were performed. Results were analyzed by one-way ANOVA in Stata12®. A significant decrease (p<0.05) of cells adhesion in relationship to FBSwas observed. However, a similar ability of cell-maintenance for PPP 10% was observed (P>0.05). Fibroblasts culture for 7 days in PRF supplemented with PPP 10% was possible, showing positive staining for Vimentin. Therefore, PPP cell supplementation decreased the initial adhesion of cells but was able to maintain the proliferation of adhered cells and able to support their viability in PRF.It seems that this method has many clinical advantagessince it provides an autologous and natural scaffold with their respective supplement for cell culture by only one process, without using xenogeneic compounds. This could improve the potential of clinical translational therapies based on the use of PRF cultured cells, promoting the regenerative potential for future use in medicine and dentistry.

Leukocyte-Reduced Platelet-Rich Plasma Alters Protein Expression of Adipose Tissue-Derived Mesenchymal Stem Cells

BACKGROUND

Application of platelet-rich plasma and stem cells has become important in regenerative medicine. Recent literature supports the use of platelet-rich plasma as a cell culture media supplement to stimulate proliferation of adipose tissue-derived mesenchymal stem cells. The underlying mechanism of proliferation stimulation by platelet-rich plasma has not been investigated so far.

METHODS

Adipose tissue-derived mesenchymal stem cells were cultured in α-minimal essential medium supplemented with platelet-rich plasma or fetal calf serum. Cell proliferation was assessed with cell cycle kinetics using flow cytometric analyses after 48 hours. Differences in proteome expression of the adipose tissue-derived mesenchymal stem cells were analyzed using a reverse-phase protein array to quantify 214 proteins. Complementary Ingenuity Pathways Analysis and gene set enrichment analysis were performed using protein data, and confirmed by Western blot analysis.

RESULTS

A higher percentage of adipose tissue-derived mesenchymal stem cells in the S phase in the presence of platelet-rich plasma advocates the proliferation stimulation. Ingenuity Pathways Analysis and gene set enrichment analysis confirm the involvement of the selected proteins in the process of cell growth and proliferation. Ingenuity Pathways Analysis revealed a participation in the top-ranked canonical pathways PI3K/AKT, PTEN, ILK, and IGF-1. Gene set enrichment analysis identified the authors' protein set as being part of significantly regulated protein sets with the focus on cell cycle, metabolism, and the Kyoto Encyclopedia of Genes and Genomes transforming growth factor-β signaling pathway.

CONCLUSIONS

The present study provides evidence that platelet-rich plasma stimulates proliferation and induces a unique change in the proteomic profile of adipose tissue-derived mesenchymal stem cells. The interpretation of altered expression of regulatory proteins represents a step forward toward achieving good manufacturing practice-compliant criteria for cell-based strategies.

Making the Switch: Alternatives to Fetal Bovine Serum for Adipose-Derived Stromal Cell Expansion

Adipose-derived stromal cells (ASCs) are being used extensively in clinical trials. These trials require that ASCs are prepared using good manufacturing practices (GMPs) and are safe for use in humans. The majority of clinical trials in which ASCs are expanded make use of fetal bovine serum (FBS). While FBS is used traditionally in the research setting for in vitro expansion, it does carry the risk of xenoimmunization and zoonotic transmission when used for expanding cells destined for therapeutic purposes. In order to ensure a GMP quality product for cellular therapy, in vitro expansion of ASCs has been undertaken using xeno-free (XF), chemically-defined, and human blood-derived alternatives. These investigations usually include the criteria proposed by the International Society of Cellular Therapy (ISCT) and International Fat Applied Technology Society (IFATS). The majority of studies use these criteria to compare plastic-adherence, morphology, the immunophenotype and the trilineage differentiation of ASCs under the different medium supplemented conditions. Based on these studies, all of the alternatives to FBS seem to be suitable replacements; however, each has its own advantages and drawbacks. Very few studies have investigated the effects of the supplements on the immunomodulation of ASCs; the transcriptome, proteome and secretome; and the ultimate effects in appropriate animal models. The selection of medium supplementation will depend on the downstream application of the ASCs and their efficacy and safety in preclinical studies.

Platelet-Rich Plasma Increases Growth and Motility of Adipose Tissue-Derived Mesenchymal Stem Cells and Controls Adipocyte Secretory Function

Adipose tissue‐derived mesenchymal stem cells (Ad‐MSC) and platelet derivatives have been used alone or in combination to achieve regeneration of injured tissues. We have tested the effect of platelet‐rich plasma (PRP) on Ad‐MSC and adipocyte function. PRP increased Ad‐MSC viability, proliferation rate and G1‐S cell cycle progression, by at least 7‐, 2‐, and 2.2‐fold, respectively, and reduced caspase 3 cleavage. Higher PRP concentrations or PRPs derived from individuals with higher platelet counts were more effective in increasing Ad‐MSC growth. PRP also accelerated cell migration by at least 1.5‐fold. However, PRP did not significantly affect mature adipocyte viability, differentiation and expression levels of PPAR‐γ and AP‐2 mRNAs, while it increased leptin production by 3.5‐fold. Interestingly, PRP treatment of mature adipocytes also enhanced the release of Interleukin (IL)‐6, IL‐8, IL‐10, Interferon‐γ, and Vascular Endothelial Growth Factor. Thus, data are consistent with a stimulatory effect of platelet derivatives on Ad‐MSC growth and motility. Moreover, PRP did not reduce mature adipocyte survival and increased the release of pro‐angiogenic factors, which may facilitate tissue regeneration processes. © 2015 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc. J. Cell. Biochem. 116: 2408–2418, 2015. © 2015 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.

Human platelet releasates combined with polyglycolic acid scaffold promote chondrocyte differentiation and phenotypic maintenance

In the present study, we aimed to demonstrate the differentiating properties of platelet-rich plasma releasates (PRPr) on human chondrocytes seeded on a polygtlycolic acid (PGA) 3D scaffold. Gene expression and biochemical analysis were carried out to assess the improved quality of our PGA-based cartilage constructs supplemented with PRPr. We observed that the use of PRPr as cell cultures supplementation to PGA-chondrocyte constructs may promote chondrocyte differentiation, and thus may contribute to maintaining the chondrogenic phenotype longer than conventional supplementation by increasing high levels of important chondrogenic markers (e.g. sox9, aggrecan and type II collagen), without induction of type I collagen. Moreover, our constructs were analysed for the secretion and deposition of important ECM molecules (sGAG, type II collagen, etc.). Our results indicate that PRPr supplementation may synergize with PGA-based scaffolds to stimulate human articular chondrocyte differentiation, maturation and phenotypic maintenance.

From bench to bedside: use of human adipose-derived stem cells

Since the discovery of adipose-derived stem cells (ASC) in human adipose tissue nearly 15 years ago, significant advances have been made in progressing this promising cell therapy tool from the laboratory bench to bedside usage. Standardization of nomenclature around the different cell types used is finally being adopted, which facilitates comparison of results between research groups. In vitro studies have assessed the ability of ASC to undergo mesenchymal differentiation as well as differentiation along alternate lineages (transdifferentiation). Recently, focus has shifted to the immune modulatory and paracrine effects of transplanted ASC, with growing interest in the ASC secretome as a source of clinical effect. Bedside use of ASC is advancing alongside basic research. An increasing number of safety-focused Phase I and Phase IIb trials have been published without identifying any significant risks or adverse events in the short term. Phase III trials to assess efficacy are currently underway. In many countries, regulatory frameworks are being developed to monitor their use and assure their safety. As many trials rely on ASC injected at a distant site from the area of clinical need, strategies to improve the homing and efficacy of transplanted cells are also being explored. This review highlights each of these aspects of the bench-to-bedside use of ASC and summarizes their clinical utility across a variety of medical specialties.

Enhanced angiogenesis in ischemic skeletal muscle after transplantation of cell sheets from baculovirus-transduced adipose-derived stromal cells expressing VEGF165

Introduction

Cell therapy using adipose-derived stromal cells (ADSC) is an intensively developing approach to promote angiogenesis and regeneration. Administration technique is crucial and among others minimal constructs - cell sheets (CS) have certain advantages. Delivery of CS allows transplantation of cells along with matrix proteins to facilitate engraftment. Cells’ therapeutic potential can be also increased by expression of proangiogenic factors by viral transduction. In this work we report on therapeutic efficacy of CS from mouse ADSC transduced to express human vascular endothelial growth factor 165 a/a isoform (VEGF165), which showed potency to restore perfusion and protect tissue in a model of limb ischemia.

Methods

Mouse ADSC (mADSC) isolated from C57 male mice were expanded for CS formation (10⁶cells per CS). Constructs were transduced to express human VEGF165 by baculoviral (BV) system. CS were transplanted subcutaneously to mice with surgically induced limb ischemia and followed by laser Doppler perfusion measurements. At endpoint animals were sacrificed and skeletal muscle was evaluated for necrosis and vessel density; CS with underlying muscle was stained for apoptosis, proliferation, monocytes and blood vessels.

Results

Using BV system and sodium butyrate treatment we expressed human VEGF165 in mADSC (production of VEGF165 reached ≈ 25-27 ng/ml/10⁵ cells) and optimized conditions to ensure cells’ viability after transduction. Implantation of mock-transduced CS resulted in significant improvement of limb perfusion, increased capillary density and necrosis reduction at 2 weeks post-surgery compared to untreated animals. Additional improvement of blood flow and angiogenesis was observed after transplantation of VEGF165-expressing CS indicating enhanced therapeutic potential of genetically modified constructs. Moreover, we found delivery of mADSC as CS to be superior to equivalent dose of suspended cells in terms of perfusion and angiogenesis. Histology analysis of extracted CS detected limited proliferation and approximately 10 % prevalence of apoptosis in transplanted mADSC. Significant vascularization of CS and infiltration by monocytes were found in both – BV-transduced and control CS indicating graft and host interaction after transplantation.

Conclusions

Delivery of ADSC by subcutaneous transplantation of CS is effective for stimulation of angiogenesis and tissue protection in limb ischemia with a potential for efficacy improvement by BV transduction to express VEGF165.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0199-6) contains supplementary material, which is available to authorized users.

Human adipose tissue-derived stem cells cultured in xeno-free culture condition enhance c-MYC expression increasing proliferation but bypassing spontaneous cell transformation

Introduction

Human adipose tissue-derived stem cells (hASCs) are attractive cells for therapeutic applications and are currently being evaluated in multiple clinical trials. Prior to their clinical application, hASCs must be expanded ex vivo to obtain the required number of cells for transplantation. Fetal bovine serum is the supplement most widely used for cell culture, but it has disadvantages and it is not safe for cell therapy due to the risks of pathogen transmission and immune reaction. Furthermore, the cell expansion poses a risk of accumulating genetic abnormalities that could lead to malignant cell transformation. In this study, our aim was to evaluate the proliferation pattern as well as the resistance to spontaneous transformation of hASCs during expansion in a xeno-free culture condition.

Methods

hASCs were expanded in Dulbecco’s modified Eagle’s medium supplemented with pooled allogeneic human serum or fetal bovine serum to enable a side-by-side comparison. Cell viability and differentiation capacity toward the mesenchymal lineages were assessed, along with immunophenotype. Ki-67 expression and the proliferation kinetics were investigated. The expression of the transcription factors c-FOS and c-MYC was examined with Western blot, and MYC, CDKN2A, ERBB2 and TERT gene expression was assessed with quantitative PCR. Senescence was evaluated by β-gal staining. Karyotype analysis was performed and tumorigenesis assay in vivo was also evaluated.

Results

The hASCs expanded in medium with pooled allogeneic human serum did not show remarkable differences in morphology, viability, differentiation capacity or immunophenotype. The main difference observed was a significantly higher proliferative effect on hASCs cultured in pooled allogeneic human serum. There was no significant difference in C-FOS expression; however, C-MYC protein expression was enhanced in pooled allogeneic human serum cultures compared to fetal bovine serum cultures. No difference was observed in MYC and TERT mRNA levels. Moreover, the hASCs presented normal karyotype undergoing senescence, and did not form in vivo tumors, eliminating the possibility that spontaneous immortalization of hASCs had occurred with pooled allogeneic human serum.

Conclusions

This complete characterization of hASCs cultivated in pooled allogeneic human serum, a suitable xeno-free approach, shows that pooled allogeneic human serum provides a high proliferation rate, which can be attributed for the first time to C-MYC protein expression, and showed cell stability for safe clinical applications in compliance with good manufacturing practice.