The correlation between human adipose-derived stem cells differentiation and cell adhesion mechanism

Gentamicin-Releasing Titania Nanotube Surfaces Inhibit Bacteria and Support Adipose-Derived Stem Cell Growth in Cocultures

Infection is the second leading cause of failure of orthopedic implants following incomplete osseointegration. Materials that increase the antimicrobial properties of surfaces while maintaining the ability for bone cells to attach and proliferate could reduce the failure rates of orthopedic implants. In this study, titania nanotubes (Nts) were modified with chitosan/heparin polyelectrolyte multilayers (PEMs) for gentamicin delivery. The antimicrobial activity of the surfaces was tested by coculturing bacteria with mammalian cells. Over 60% of gentamicin remained on the surface after an initial burst release on the first day. Antimicrobial activity of these surfaces was determined by exposure to Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) for up to 24 h. Gentamicin surfaces had less live E. coli and S. aureus by 6 h and less E. coli by 24 h compared to Nt surfaces. S. aureus and human adipose-derived stem cells (hADSCs) were cocultured on surfaces for up to 7 days to characterize the so-called "race to the surface" between bacteria and mammalian cells, which is hypothesized to ultimately determine the outcome of orthopedic implants. By day 7, there was no significant difference in bacteria between surfaces with gentamicin adsorbed on the surface and surfaces with gentamicin in solution. However, gentamicin delivered in solution is toxic to hADSCs. Alternatively, gentamicin presented from PEMs enhances the antimicrobial properties of the surfaces without inhibiting hADSC attachment and cell growth. Delivering gentamicin from the surfaces is therefore superior to delivering gentamicin in solution and represents a strategy that could improve the antimicrobial activity of orthopedic implants and reduce risk of failure due to infection, without reducing mammalian cell attachment.

Characterization of cell signaling, morphology, and differentiation potential of human mesenchymal stem cells based on cell adhesion mechanism

It is essential to characterize the cellular properties of mesenchymal stem cell populations to maintain quality specifications and control in regenerative medicine. Biofunctional materials have been designed as artificial matrices for the stimulation of cell adhesion and specific cellular functions. We have developed recombinant maltose-binding protein (MBP)-fused proteins as artificial adhesion matrices to control human mesenchymal stem cell (hMSC) fate by using an integrin-independent heparin sulfate proteoglycans-mediated cell adhesion. In this study, we characterize cell adhesion-dependent cellular behaviors of human adipose-derived stem cells (hASCs) and human bone marrow stem cells (hBMSCs). We used an MBP-fused basic fibroblast growth factor (MF)-coated surface and fibronectin (FN)-coated surface to restrict and support, respectively, integrin-mediated adhesion. The cells adhered to MF exhibited restricted actin cytoskeleton organization and focal adhesion kinase phosphorylation. The hASCs and hBMSCs exhibited different cytoplasmic projection morphologies on MF. Both hASCs and hBMSCs differentiated more dominantly into osteogenic cells on FN than on MF. In contrast, hASCs differentiated more dominantly into adipogenic cells on MF than on FN, whereas hBMSCs differentiated predominantly into adipogenic cells on FN. The results indicate that hASCs exhibit a competitive differentiation potential (osteogenesis vs. adipogenesis) that depends on the cell adhesion matrix, whereas hBMSCs exhibit both adipogenesis and osteogenesis in integrin-mediated adhesion and thus hBMSCs have noncompetitive differentiation potential. We suggest that comparing differentiation behaviors of hMSCs with the diversity of cell adhesion is an important way to characterize hMSCs for regenerative medicine.

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.

Polypeptide Thermogels as Three-Dimensional Scaffolds for Cells

BACKGROUND

Thermogel is an aqueous solution that exhibits a sol-to-gel transition as the temperature increases. Stem cells, growth factors, and differentiating factors can be incorporated in situ in the matrix during the sol-to-gel transition, leading to the formation of a three-dimensional (3D) cell-culture scaffold.

METHODS

The uses of thermogelling polypeptides, such as collagen, Matrigel™, elastin-like polypeptides, and synthetic polypeptides, as 3D scaffolds of cells, are summarized in this paper.

RESULTS

The timely supply of growth factors to the cells, cell survival, and metabolite removal is to be insured in the cell culture matrix. Various growth factors were incorporated in the matrix during the sol-to-gel transition of the thermogelling polypeptide aqueous solutions, and preferential differentiation of the incorporated stem cells into specific target cells were investigated. In addition, modulus of the matrix was controlled by post-crosslinking reactions of thermogels or employing composite systems. Chemical functional groups as well as biological factors were selected appropriately for targeted differentiation of the incorporated stem cells.

CONCLUSION

In addition to all the advantages of thermogels including mild conditions for cell-incorporation and controlled supplies of the growth factors, polypeptide thermogels provide neutral pH environments to the cells during the degradation of the gel. Polypeptide thermogels as an injectable scaffold can be a promising system for their eventual in vivo applications in stem cell therapy.

Surface modification of PHBV nanofiber mats for rapid cell cultivation and harvesting

To maintain the original function of a specific tissue for therapeutic tissue engineering, an advanced cell culture surface for repeat cell proliferation is necessary. We designed a novel cell proliferation and rapid harvesting surface by combining nonwoven nanofiber mat and a thermo-responsive polymer. Nanofibrous poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) mats were fabricated by the electrospinning technique. A poly(N-isopropylacrylamide) (PNIPAM) thermo-responsive layer was grafted on the PHBV nanofiber mat by electron beam irradiation. The average diameter of the PNIPAM-grafted PHBV nanofibers was determined by SEM. ATR-FTIR and ESCA were used to confirm the grafting of PNIPAM onto the PHBV nanofiber surface. Water contact angles on the mats were measured in response to temperature changes. Human adipose-derived stem cells (ADSCs) were cultured on the PNIPAM-grafted PHBV nanofiber mat to investigate cell proliferation, harvesting, and functionality during repeat subculture. Detached ADSCs from each surface by low temperature treatment and trypsin-EDTA were compared by a fluorescence-activated cell sorter (FACS) using expression of stem cell membrane-specific markers such as CD-13 PE, CD-29 PE, and CD-90 FITC. The mass cultivation and intact harvesting of stem cells by low temperature treatment using a thermo-responsive PHBV nanofiber mat is a promising technique for use in regenerative medicine and stem cell therapy.

Update on the mechanisms of homing of adipose tissue-derived stem cells

Adipose tissue-derived stem cells (ADSCs), which resemble bone marrow mesenchymal stromal cells (BMSCs), have shown great advantages and promise in the field of regenerative medicine. They can be readily harvested in large numbers with low donor-site morbidity. To date, a great number of preclinical and clinical studies have shown ADSCs' safety and efficacy in regenerative medicine. However, a better understanding of the mechanisms of homing of ADSCs is needed to advance the clinical utility of this therapy. In this review, the reports of the homing of ADSCs were searched using Pubmed and Google Scholar to update our knowledge. ADSCs were proved to interact with endothelial cells by expressing the similar integrins with BMSCs. In addition, ADSCs do not possess the dominant ligand for P-selectin, just like BMSCs. Stromal derived factor-1 (SDF-1)/CXCR4 and CXC ligand-5 (CXCL5)/CXCR2 interactions are the two main axes governing ADSCs extravasation from bone marrow vessels. Some more signaling pathways involved in migration of ADSCs have been investigated, including LPA/LPA1 signaling pathway, MAPK/Erk1/2 signaling pathway, RhoA/Rock signaling pathway and PDGF-BB/PDGFR-β signaling pathway. Status quo of a lack of intensive studies on the details of homing of ADSCs should be improved in the near future before clinical application.

Heparin-hyaluronic acid hydrogel in support of cellular activities of 3D encapsulated adipose derived stem cells

We have developed stem cell-responsive, heparin-hyaluronic acid (Hep-HA) hydrogel, crosslinked by thiolated heparin (Hep-SH) and methacrylated hyaluronic acid (HA-MA) via visible light mediated, thiol-ene reaction. Physical properties of the hydrogel (gelation time, storage modulus, and swelling ratio) were tunable by adjusting light intensity, initiator/polymer concentration, and precursor pH. Culture of human adipose derived mesenchymal stem cells (ADSCs) using this hydrogel was characterized and compared with the control hydrogels including Hep-PEG hydrogel, PEG-HA hydrogel. Sufficient initial adhesion and continuous proliferation of ADSCs in 2D were observed on both heparin-containing hydrogels (Hep-HA and Hep-PEG hydrogel) in contrast to no adhesion of ADSCs on PEG-HA hydrogel. On the other hand, in the case of 3D culture of encapsulated ADSCs, efficient cellular activities such as spreading, proliferation, migration, and differentiation of ADSCs were only observed in soft Hep-HA hydrogel compared to Hep-PEG or PEG-HA hydrogel with the similar modulus. The upregulated expressions of hyaluronidases in ADSCs encapsulated in Hep-HA hydrogel compared to the control hydrogels and effective degradation of the hydrogel by hyaluronidase imply that the degradation of hydrogel was necessary for 3D cellular activities. Thus, Hep-HA hydrogel, where heparin acts as a binding domain for ADSCs and HA acts as a degradation site by cell secreted enzymes, was efficient for 3D culture of human ADSCs without any additional modification using biological/chemical molecules.

STATEMENT OF SIGNIFICANCE

Stem cell-responsive hydrogel composed of heparin and hyaluronic acid was prepared by visible light-mediated thiol-ene reaction. Without additional modification using functional peptides for cell adhesion and matrix degradation, ADSCs encapsulated in this hydrogel showed efficient cellular activities such as spreading, proliferation, migration, and differentiation of ADSCs whereas control hydrogels missing heparin or hyaluronic acid could not support cellular activities in 3D. In this hydrogel, heparin mainly acts as a binding domain for stem cells and hyaluronic acid mainly acts as a degradation site by ADSC secreted enzymes, but interrelated synergistic functions of heparin and HA were observed. Therefore, we speculate that this hydrogel can serve as a promising carrier for stem cell based therapy and various tissue engineering applications.

Zwitterionic poly(sulfobetaine methacrylate) hydrogels incorporated with angiogenic peptides promote differentiation of human adipose-derived stem cells

The superhydrophilic and ultralow biofouling properties as well as the resistance to foreign-body reaction make zwitterionic polymer promising in biomedical applications.

Laminin-Alginate Beads as Preadipocyte Carriers to Enhance Adipogenesis In Vitro and In Vivo

The use of autologous fat grafting in breast reconstruction still requires optimization. Fat survival and calcification are the main issues that affect the outcomes of the procedure. In this study, a cell-based therapy utilizing laminin-alginate beads (LABs) as carriers was proposed to promote cell survival and adipogenesis by providing short-term physical support and facilitate nutrient diffusion of the implants. Laminin-modified alginate beads were fabricated by immobilizing laminin onto ring-opened alginate, used to encapsulate 3T3-L1 preadipocytes, and evaluated in vitro and in vivo. LABs as preadipocyte carriers showed better biocompatibility and stability than unmodified alginate beads. Preadipocytes in LABs had higher survival rate and enhanced adipogenesis than those in unmodified alginate beads. In vivo studies showed that LABs gradually degraded and the sites were replaced by newly formed fat tissues, and new blood vessels were also observed. 7T-MRI study mimicking clinical fat grafting showed that LABs carrying adipose stem cells improved the results of conventional fat grafts. Therefore, we believe that LABs represent promising cell carriers and can be potentially used for the reconstruction of breasts or other soft tissues in the future.

Adipose tissue-derived stem cells ameliorates dermal fibrosis in a mouse model of scleroderma

OBJECTIVE

To investigate the therapeutic potential of adipose-derived stem cells (ADSCs) for limited cutaneous scleroderma (LS) in mouse models.

METHODS

ADSCs were isolated from pathogen-free female C57BL/6 mice and LS was induced in wild type (WT) C57BL/6 mice via daily injection of bleomycin (0.1 mL × 300 μg/mL) for 4 weeks; then the ADSCs were subcutaneously injected into the dorsal area in the model treatment group, and 100 μL of phosphate-buffered saline (PBS) solution was injected into the same site in the model control group. Green fluorescent protein (GFP) was used to track the cells using an in vivo imaging system on days 7, 14, 21, and 28 after transplantation. All mice were sacrificed and histologic analyses were performed after 4 weeks, and the skin thickness, collagen deposition and the total content of hydroxyproline were evaluated. Additionally, immunohistochemistry were performed to compare the tissue expression and distribution of TGF-β1 and VEGF between the ADSCs treatment group and the treatment control group.

RESULTS

WT C57BL/6 LS mouse model were successfully established and GFP in vivo fluorescence imaging showed that the translated ADSCs survived at the local for at least 4 weeks. Compared with the control group, the ADSCs treatment group significantly attenuated bleomycin-induced dermal fibrosis, reduced the skin thickness and the total content of hydroxyproline (P < 0.05). The ADSCs treatment group displayed significantly lower levels of TGF-β1 and higher levels of VEGF than the control group (P < 0.05).

CONCLUSIONS

ADSCs may provide a feasible and practical treatment for autoimmune diseases such as LS and ameliorate dermal fibrosis.

Heparan sulfates and the decrease of N-glycans promote early adipogenic differentiation rather than myogenesis of murine myogenic progenitor cells

In vitro, extracted muscle satellite cells, called myogenic progenitor cells, can differentiate either in myotubes or preadipocytes, depending on environmental factors and the medium. Transcriptomic analyses on glycosylation genes during satellite cells differentiation into myotubes showed that 31 genes present a significant variation of expression at the early stages of murine myogenic progenitor cells (MPC) differentiation. In the present study, we analyzed the expression of 383 glycosylation related genes during murine MPC differentiation into preadipocytes and compared the data to those previously obtained during their differentiation into myotubes. Fifty-six glycosylation related genes are specifically modified in their expression during early adipogenesis. The variations correspond mainly to: a decrease of N-glycans, and of alpha (2,3) and (2,6) linked sialic acids, and to a high level of heparan sulfates. A high amount of TGF-β1 in extracellular media during early adipogenesis was also observed. It seems that the increases of heparan sulfates and TGF-β1 favor pre-adipogenic differentition of MPC and possibly prevent their myogenic differentiation.

Combinatorial therapy with three-dimensionally cultured adipose-derived stromal cells and self-assembling peptides to enhance angiogenesis and preserve cardiac function in infarcted hearts

Even though stem cell therapy is a promising angiogenic strategy to treat ischaemic diseases, including myocardial infarction (MI), therapeutic efficacy is limited by low survival and retention of transplanted cells in ischaemic tissues. In addition, therapeutic angiogenesis depends on stimulating host angiogenesis with paracrine factors released by transplanted cells rather than on direct blood vessel formation by transplanted cells. In the present study, to overcome these limitations and to enhance the therapeutic efficacy of MI treatment, combinatorial therapy with three-dimensional cell masses (3DCMs) and self-assembling peptides (SAPs) was tested in a rat MI model. Spheroid-type 3DCMs, which are vascular differentiation-induced cells, were prepared by culturing human adipose-derived stromal cells on a fibroblast growth factor-immobilized surface. The SAPs were used as the carrier material to increase engraftment of transplanted cells. After coronary artery ligation, 3DCMs were combined with SAPs and were transplanted into ischaemic lesions. The therapeutic potential was evaluated 4 weeks after treatment. By combining 3DCMs and SAPs, survival and retention of transplanted cells increased threefold when compared with treatment with 3DCMs alone and transplanted cells established vascular networks in infarcted hearts. In addition, the size of the infarct in the 3DCM + SAP group was reduced to 6.09 ± 2.83% by the promotion of host angiogenesis and cardiac function was preserved, as demonstrated by a 54.25 ± 4.42% increase in the ejection fraction. This study indicates that combinatorial therapy with 3DCM and SAPs could be a promising strategy for therapeutic angiogenesis to treat MI. Copyright © 2016 John Wiley & Sons, Ltd.

Prevention of skin flap necrosis by use of adipose-derived stromal cells with light-emitting diode phototherapy

BACKGROUND AIMS

The aim of this study was to investigate the effects of low-level light therapy (LLLT) on transplanted human adipose-derived mesenchymal stromal cells (ASCs) in the skin flap of mice.

METHODS

LLLT, ASC transplantation and ASC transplantation with LLLT (ASC + LLLT) were applied to the skin flap. Immunostaining and Western blot analysis were performed to evaluate cell survival and differentiation and secretion of vascular endothelial growth factor and basic fibroblast growth factor by the ASCs. Vascular regeneration was assessed by means of immunostaining in addition to hematoxylin and eosin staining. In the ASC + LLLT group, the survival of ASCs was increased as the result of the decreased apoptosis of ASCs.

RESULTS

The secretion of growth factors was higher in this group as compared with ASCs alone. ASCs contributed to tissue regeneration through vascular cell differentiation and secretion of angiogenic growth factors. The ASC + LLLT group displayed improved treatment efficacy including neovascularization and tissue regeneration compared with ASCs alone. Transplanting ASCs to ischemic skin flaps improved therapeutic efficacy for ischemia treatment as the result of enhanced cell survival and paracrine effects.

CONCLUSIONS

These data suggest that LLLT is an effective biostimulator of ASCs in vascular regeneration, which enhances the survival of ASCs and stimulates the secretion of growth factors in skin flaps.

Biomimetic 3D tissue printing for soft tissue regeneration

Engineered adipose tissue constructs that are capable of reconstructing soft tissue with adequate volume would be worthwhile in plastic and reconstructive surgery. Tissue printing offers the possibility of fabricating anatomically relevant tissue constructs by delivering suitable matrix materials and living cells. Here, we devise a biomimetic approach for printing adipose tissue constructs employing decellularized adipose tissue (DAT) matrix bioink encapsulating human adipose tissue-derived mesenchymal stem cells (hASCs). We designed and printed precisely-defined and flexible dome-shaped structures with engineered porosity using DAT bioink that facilitated high cell viability over 2 weeks and induced expression of standard adipogenic genes without any supplemented adipogenic factors. The printed DAT constructs expressed adipogenic genes more intensely than did non-printed DAT gel. To evaluate the efficacy of our printed tissue constructs for adipose tissue regeneration, we implanted them subcutaneously in mice. The constructs did not induce chronic inflammation or cytotoxicity postimplantation, but supported positive tissue infiltration, constructive tissue remodeling, and adipose tissue formation. This study demonstrates that direct printing of spatially on-demand customized tissue analogs is a promising approach to soft tissue regeneration.

Adhesion of adipose-derived mesenchymal stem cells to glycosaminoglycan surfaces with different protein patterns

Proteins and glycosaminoglycans (GAGs) are the main constituents of the extracellular matrix (ECM). They act in synergism and are equally critical for the development, growth, function, or survival of an organism. In this work, we developed surfaces that display these two classes of biomacromolecules, namely, GAGs and proteins, in a spatially controlled fashion. The generated surfaces can be used as a minimalistic but straightforward model aiding the elucidation of cell-ECM interactions. GAGs (hyaluronic acid and heparin) were covalently bound to amino functionalized surfaces, and albumin or fibronectin was patterned by microcontact printing on top of them. We demonstrate that adipose-derived stem cells (ASCs) can adhere either on the protein or on the GAG pattern as a function of the patterned molecules. ASCs found on the GAG pattern had different morphology and expressed different surface markers than the cells adhered on the protein pattern. ASCs morphology and spreading were also dependent on the size of the pattern. These results show that the developed supports can also be used for ASCs differentiation into different lineages.

Union is strength: matrix elasticity and microenvironmental factors codetermine stem cell differentiation fate

Stem cells are an attractive cellular source for regenerative medicine and tissue engineering applications due to their multipotency. Although the elasticity of the extracellular matrix (ECM) has been shown to have crucial impacts in directing stem cell differentiation, it is not the only contributing factor. Many researchers have recently attempted to design microenvironments that mimic the stem cell niche with combinations of ECM elasticity and other cues, such as ECM physical properties, soluble biochemical factors and cell-cell interactions, thereby driving cells towards their preferred lineages. Here, we briefly discuss the effect of matrix elasticity on stem cell lineage specification and then summarize recent advances in the study of the combined effects of ECM elasticity and other cues on the differentiation of stem cells, focusing on two aspects: biophysical and biochemical factors. In the future, biomedical scientists will continue investigating the union strength of matrix elasticity and microenvironmental cues for manipulating stem cell fates.

Exendin-4 pretreated adipose derived stem cells are resistant to oxidative stress and improve cardiac performance via enhanced adhesion in the infarcted heart

Reactive oxygen species (ROS), which were largely generated after myocardial ischemia, severely impaired the adhesion and survival of transplanted stem cells. In this study, we aimed to determine whether Exendin-4 pretreatment could improve the adhesion and therapeutic efficacy of transplanted adipose derived stem cells (ADSCs) in ischemic myocardium. In vitro, H2O2 was used to provide ROS environments, in which ADSCs pretreated with Exendin-4 were incubated. ADSCs without pretreatment were used as control. Then, cell adhesion and viability were analyzed with time. Compared with control ADSCs, Exendin-4 treatment significantly increased the adhesion of ADSCs in ROS environment, while reduced intracellular ROS and cell injury as determined by dihydroethidium (DHE) staining live/Dead staining, lactate dehydrogenase-release assay and MTT assay. Western Blotting demonstrated that ROS significantly decreased the expression of adhesion-related integrins and integrin-related focal adhesion proteins, which were significantly reversed by Exendin-4 pretreatment and followed by decreases in caspase-3, indicating that Exendin-4 may facilitate cell survival through enhanced adhesion. In vivo, myocardial infarction (MI) was induced by the left anterior descending artery ligation in SD rats. Autologous ADSCs with or without Exendin-4 pretreatment were injected into the border area of infarcted hearts, respectively. Multi-techniques were used to assess the beneficial effects after transplantation. Longitudinal bioluminescence imaging and histological staining revealed that Exendin-4 pretreatment enhanced the survival and differentiation of engrafted ADSCs in ischemic myocardium, accompanied with significant benefits in cardiac function, matrix remodeling, and angiogenesis compared with non-pretreated ADSCs 4 weeks post-transplantation. In conclusion, transplantation of Exendin-4 pretreated ADSCs significantly improved cardiac performance and can be an innovative approach in the clinical perspective.

Printing three-dimensional tissue analogues with decellularized extracellular matrix bioink

The ability to print and pattern all the components that make up a tissue (cells and matrix materials) in three dimensions to generate structures similar to tissues is an exciting prospect of bioprinting. However, the majority of the matrix materials used so far for bioprinting cannot represent the complexity of natural extracellular matrix (ECM) and thus are unable to reconstitute the intrinsic cellular morphologies and functions. Here, we develop a method for the bioprinting of cell-laden constructs with novel decellularized extracellular matrix (dECM) bioink capable of providing an optimized microenvironment conducive to the growth of three-dimensional structured tissue. We show the versatility and flexibility of the developed bioprinting process using tissue-specific dECM bioinks, including adipose, cartilage and heart tissues, capable of providing crucial cues for cells engraftment, survival and long-term function. We achieve high cell viability and functionality of the printed dECM structures using our bioprinting method.

A novel three-dimensional adipose-derived stem cell cluster for vascular regeneration in ischemic tissue

BACKGROUND AIMS

Stem cells are one of the most powerful tools in regeneration medicine. However, many limitations remain regarding the use of adult stem cells in clinical applications, including poor cell survival and low treatment efficiency. We describe an innovative three-dimensional cell mass (3DCM) culture that is based on cell adhesion (basic fibroblast growth factor-immobilized substrate) and assess the therapeutic potential of 3DCMs composed of human adipose tissue-derived stromal cells (hASCs).

METHODS

For formation of a 3DCM, hASCs were cultured on a substrate with immobilized fibroblast growth factor-2. The angiogenic potential of 3DCMs was determined by immunostaining, fluorescence-activated cell sorting and protein analysis. To evaluate the vasculature ability and improved treatment efficacy of 3DCMs, the 3DCMs were intramuscularly injected into the ischemic limbs of mice.

RESULTS

The 3DCMs released various angiogenic factors (eg, vascular endothelial growth factor and interleukin-8) and differentiated into vascular cells within 3 days in normal medium. Blood vessel and tissue regeneration was clearly observed through visual inspection in the 3DCM-injected group. hASC injection slowed limb necrosis after treatment, but 50% of the mice ultimately had limb loss within 28 days. Most mice receiving 3DCMs had limb salvage (89%) or mild limb necrosis (11%).

CONCLUSIONS

3DCM culture promotes the efficient vascular differentiation of stem cells, and 3DCM transplantation results in the direct vascular regeneration of the injected cells and an improved therapeutic efficacy.

Human mesenchymal stem cell culture on heparin-based hydrogels and the modulation of interactions by gel elasticity and heparin amount

Human adipose-derived stem cells (hADSCs) are a promising cell source for tissue engineering and regenerative medicine with no ethnical issue and easy access of large quantities. Conventional surfaces for hADSC culture, such as tissue culture plates (TCPs), do not provide optimal environmental cues, leading to limited expansion, loss of pluripotency and undesirable differentiation of stem cells. The present study demonstrated that heparin-based hydrogels without additional modification provided an excellent surface for adhesion and proliferation of hADSCs, which were further tunable by both the amount of heparin (in a positive way) and the elasticity of hydrogel (in a negative way). The optimized heparin-based hydrogel could selectively modulate the adhesion of hADSCs and human bone marrow stem cells (but not all kinds of cells), and resulted in a significant increase in cell proliferation compared to TCP. Furthermore, in terms of the maintenance of pluripotency and specific differentiation, heparin-based hydrogel was much superior to TCP. The selective binding and proliferation of human mesenchymal stem cells on heparin-based hydrogel over other hydrogels were largely mediated by integrin β1 and selectin, and these superior characteristics were observed regardless of the presence of serum proteins in the culture medium. Consequently, heparin-based hydrogel could be a powerful platform for cultivation of mesenchymal stem cells in various applications.

Development of fully defined xeno-free culture system for the preparation and propagation of cell therapy-compliant human adipose stem cells

Introduction

Adipose tissue is an attractive and abundant source of multipotent stem cells. Human adipose stem cells (ASCs) have shown to have therapeutic relevancy in diverse clinical applications. Nevertheless, expansion of ASCs is often necessary before performing clinical studies. Standard in vitro cell-culture techniques use animal-derived reagents that should be avoided in clinical use because of safety issues. Therefore, xeno- and serum-free (XF/SF) reagents are highly desirable for enhancing the safety and quality of the transplanted ASCs.

Methods

In the current study, animal component-free isolation and cell-expansion protocols were developed for ASCs. StemPro MSC SFM XF medium with either CELLstart™ CTS™ coating or Coating Matrix Kit were tested for their ability to support XF/SF growth. Basic stem-cell characteristics such as immunophenotype (CD3, CD11a, CD14, CD19, CD34, CD45RO, CD54, CD73, CD80, CD86, CD90, CD105, HLA-DR), proliferation, and differentiation potential were assessed in XF/SF conditions and compared with human serum (HS) or traditionally used fetal bovine serum (FBS) cultures.

Results

ASCs cultured in XF/SF conditions had significantly higher proliferation rates compared with HS/FBS cultures. Characteristic immunophenotypes of ASCs were maintained in every condition; however, cells expanded in XF/SF conditions showed significantly lower expression of CD54 (intercellular adhesion molecule 1, ICAM-1) at low passage number. Further, multilineage differentiation potential of ASCs was maintained in every culture condition.

Conclusions

Our findings demonstrated that the novel XF/SF conditions maintained the basic stem cell features of ASCs and the animal-free workflow followed in this study has great potential in clinical cell therapies.

Therapeutic angiogenesis of three-dimensionally cultured adipose-derived stem cells in rat infarcted hearts

BACKGROUND AIMS

To successfully treat myocardial infarction (MI), blood must be resupplied to the ischemic myocardium by inducing angiogenesis. Many studies report enhanced angiogenesis using stem cells; however, the therapeutic efficacy of cell transplant remains low because transplanted cells may not survive, be retained at the site of transplant, or develop into vascular tissue. In this study, we assessed the therapeutic potential of three-dimensional cell masses (3DCM) composed of human adipose-derived stem cells (hASC) in a rat MI model.

METHODS

For formation of 3DCM, hASC were cultured on a substrate with immobilized fibroblast growth factor 2. The morphology and phenotypes of 3DCM were analyzed 1 day after culture. The cells (hASC and 3DCM, 5 × 10(5) cells) were injected into ischemic regions after ligation of the left coronary artery (n = 6 in each group). Cell retention ratio, therapeutic efficacy and vascularization were evaluated 4 weeks after transplant.

RESULTS

A spheroid-type 3DCM, which included vascular cells (CD34(+)/CD31(+)/KDR(+)/α-SMA(+)) with high production of human vascular endothelial growth factor, was obtained. Infarct size and cardiomyocyte apoptosis were reduced in the 3DCM-injected group compared with the hASC-injected group. The retention ratio of hASC was 14-fold higher in the 3DCM-injected group. Many transplanted cells differentiated into endothelial and smooth muscle cells and formed vascular networks incorporated into host vessels.

CONCLUSIONS

Transplant of 3DCM may be useful for angiogenic cell therapy to treat MI.

Transplantation of an adipose stem cell cluster in a spinal cord injury

We investigated whether transplantation of a three-dimensional cell mass of adipose-derived stem cells (3DCM-ASCs) improved hind limb functional recovery by the stimulation of angiogenesis and neurogenesis in a spinal cord injury. In in-vitro experiments, we confirmed that 3DCM-ASCs differentiated into CD31-positive endothelial cells. To evaluate the therapeutic effect of 3DCM-ASCs in vivo, PBS, human adipose tissue-derived stem cells, and 3DCM-ASCs were transplanted into a spinal cord injury model. The 3DCM-ASCs transplanted into the injured spinal cord differentiated into CD31-positive endothelial cells and remained differentiated. Transplantation of 3DCM-ASCs into the injured spinal cord significantly elevated the density of vascular formations through angiogenic factors released by the 3DCM-ASCs at the lesion site, and enhanced axonal outgrowth at the lesion site. Consistent with these results, the transplantation of 3DCM-ASCs significantly improved functional recovery compared with both ASC transplantation and PBS treatment. These findings suggest that transplantation of 3DCM-ASCs may be an effective stem cell therapy for the treatment of spinal cord injuries and neural ischemia.

Adhesion and differentiation of adipose-derived stem cells on a substrate with immobilized fibroblast growth factor

Control of cell-matrix interactions plays a role in the regulation of stem cell function. In this study basic fibroblast growth factor (bFGF) linked to maltose-binding protein (MBP) was designed as a matrix for cell adhesion. MBP-FGF was immobilized on polystyrene (PS) surfaces by spontaneous adsorption. The amount of MBP-bFGF immobilized on the PS surface increased with increasing protein concentration, being 158 ng cm(-2) at 10 μg ml(-1) protein. Human adipose-derived stem cell (hASC) adhesion to MBP-bFGF immobilized on a PS surface (PS-MBP-bFGF) was inhibited by heparin. Integrin signaling and cell spreading of hASC on PS-MBP-bFGF were down-regulated compared with those on fibronectin-coated surfaces or tissue culture polystyrene (TCP). hASC differentiated into adipocytes, which stained positive for lipid vacuoles with Oil Red, more readily on PS-MBP-bFGF than on TCP. In contrast, hASC hardly differentiated into osteoblast on PS-MBP-bFGF or on TCP. These results suggest that the mechanism of hASC adhesion to MBP-bFGF immobilized on a PS substrate is mediated by a specific interaction between bFGF and heparin, and that the adhesion mechanism might provide an insight into the design of biomaterials to control the fate of stem cells.

Human platelet lysate as a fetal bovine serum substitute improves human adipose-derived stromal cell culture for future cardiac repair applications

Adipose-derived stromal cells (ASC) are promising candidates for cell therapy, for example to treat myocardial infarction. Commonly, fetal bovine serum (FBS) is used in ASC culturing. However, FBS has several disadvantages. Its effects differ between batches and, when applied clinically, transmission of pathogens and antibody development against FBS are possible. In this study, we investigated whether FBS can be substituted by human platelet lysate (PL) in ASC culture, without affecting functional capacities particularly important for cardiac repair application of ASC. We found that PL-cultured ASC had a significant 3-fold increased proliferation rate and a significantly higher attachment to tissue culture plastic as well as to endothelial cells compared with FBS-cultured ASC. PL-cultured ASC remained a significant 25% smaller than FBS-cultured ASC. Both showed a comparable surface marker profile, with the exception of significantly higher levels of CD73, CD90, and CD166 on PL-cultured ASC. PL-cultured ASC showed a significantly higher migration rate compared with FBS-cultured ASC in a transwell assay. Finally, FBS- and PL-cultured ASC had a similar high capacity to differentiate towards cardiomyocytes. In conclusion, this study showed that culturing ASC is more favorable in PL-supplemented medium compared with FBS-supplemented medium.

Production of human tissue-engineered skin trilayer on a plasma-based hypodermis

Full thickness wounds require a dermal component to achieve functional permanent skin restoration. Currently available tissue-engineered skin substitutes lack a subcutaneous fat layer that would functionally contribute some of the mechanical and thermoregulatory properties of normal skin. To generate a trilayer engineered skin equivalent, we included bone marrow mesenchymal (BM-MSC) or adipose tissue-derived (ASC) stromal cells in a human plasma hydrogel exposed to adipogenic clues for three weeks. Approximately half of the cells differentiated under these conditions into mature adipocytes that survived for two years in culture with minimal medium change. In vitro generation of bona fide fully differentiated adipocytes was assessed by leptin secretion and ultrastructurally demonstrated through semithin to ultrathin sectioning and lipid staining with osmium tetroxide. Furthermore, presence of BM-MSCs or ASCs within the subcutaneous layer contributed to the epidermal differentiation program, with more proliferating basal cells depositing basal membrane proteins and differentiating into mature keratinocytes that were able to generate a pluristratified epithelium. In conclusion, we engineered a fully differentiated human skin trilayer that could present multiple applications such as use for in vitro drug absorption tests and regenerative therapies.

RPTPμ tyrosine phosphatase promotes adipogenic differentiation via modulation of p120 catenin phosphorylation

Adipocyte differentiation can be regulated by the combined activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). In particular, PTPs act as key regulators in differentiation-associated signaling pathways. We recently found that receptor-type PTPμ (RPTPμ) expression is markedly increased during the adipogenic differentiation of 3T3-L1 preadipocytes and mesenchymal stem cells. Here, we investigate the functional roles of RPTPμ and the mechanism of its involvement in the regulation of signal transduction during adipogenesis of 3T3-L1 cells. Depletion of endogenous RPTPμ by RNA interference significantly inhibited adipogenic differentiation, whereas RPTPμ overexpression led to an increase in adipogenic differentiation. Ectopic expression of p120 catenin suppressed adipocyte differentiation, and the decrease in adipogenesis by p120 catenin was recovered by introducing RPTPμ. Moreover, RPTPμ induced a decrease in the cytoplasmic p120 catenin expression by reducing its tyrosine phosphorylation level, consequently leading to enhanced translocation of Glut-4 to the plasma membrane. On the basis of these results, we propose that RPTPμ acts as a positive regulator of adipogenesis by modulating the cytoplasmic p120 catenin level. Our data conclusively demonstrate that differentiation into adipocytes is controlled by RPTPμ, supporting the utility of RPTPμ and p120 catenin as novel target proteins for the treatment of obesity.

Monitoring human mesenchymal stromal cell differentiation by electrochemical impedance sensing

BACKGROUND AIMS

For their wide mesodermal differentiation potential, mesenchymal stromal/stem cells (MSC) are attractive candidates for tissue engineering. However, standardized quality control assays monitoring differentiation that are non-invasive and continuous over time are lacking.

METHODS

We employed a non-invasive assay, using two different systems, to discriminate osteogenic and adipogenic differentiation of MSC by monitoring impedance. Fibroblasts and keratinocytes served as non-specific controls. Impedance profiles were recorded comparing MSC from bone marrow and adipose tissue, either non-induced or induced for osteogenesis or adipogenesis, for 5-14 days, and correlated with differentiation markers assessed by reverse transcription-quantitative polymerase chain reaction and Western blot. Additionally, differentiation modulating effects of extracellular matrix components were analyzed.

RESULTS

Adhesion and growth-related impedance profiles of non-induced MSC roughly resembled those of fibroblasts, whereas keratinocytes differed significantly. Distinct from that, osteogenic induction of MSC revealed initially rapid and continuously rising impedance, corresponding to mineralized calcium matrix formation. Conversely, adipogenic induction caused shallower initial slopes and eventually declining profiles, corresponding to more compact, adipocyte-like cells with numerous lipid vacuoles. Pre-coating with either collagen type I or IV apparently favored osteogenesis and fibronectin adipogenesis. Impedance recordings correlated well with the extent of differentiation evaluated by histochemical staining and protein and gene expression.

CONCLUSIONS

Overall, our data demonstrate that impedance profiling offers a basis for standardized real-time, non-invasive high-throughput screening of MSC properties. It enables further testing of the influence of diffusible factors or extracellular matrix composites on MSC differentiation or maintenance of stemness, thus substantiating therapeutic application.

Mesenchymal stem cells, osteoblasts and extracellular matrix proteins: enhancing cell adhesion and differentiation for bone tissue engineering

Cell adhesion to scaffolds has remained one of the challenges in tissue engineering. Although protein surface modification has been proven to enhance cell adhesion and retention, its specificity depending on cell and biomaterial types means that the best protein and concentration must be established for each specific application. This review focuses on the improvement of cell adhesion for human mesenchymal stem cells with an osteogenesis approach. A brief outline of the cell adhesion process and extracellular matrix proteins precedes an overview of works focused on the adhesion of mesenchymal stem cells and osteoblasts to biomaterials and this effect in their differentiation into osteoblasts.

Osteoblasts on rod shaped hydroxyapatite nanoparticles incorporated PCL film provide an optimal osteogenic niche for stem cell differentiation

After the clinical insertion of a bone biomaterial, the surrounding osteoblasts would migrate and attach to the implant surface and foster a microenvironment that largely determines the differentiation fate of the comigrated mesenchymal stem cells. Whether the fostered microenvironment is suitable for osteogenic differentiation of mesenchymal stem cells is critical for the subsequent osseointegration. In this study, we determined (1) how the spherical or rod-shaped hydroxyapatite nanoparticles (nHA) incorporated poly(ɛ-caprolactone) (PCL) films (PCL-spherical nHA, PCL-rod nHA) interact with primary human osteoblasts (HOBs); (2) how the microenvironment rendered by their interaction affects osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ASCs). HOBs were seeded on PCL, PCL-spherical nHA, and PCL-rod nHA films, respectively. When cultured alone, the HOBs on PCL-rod nHA films showed most efficient osteoblastic differentiation compared with those on PCL or PCL-spherical nHA films. When cocultured with ASCs in an indirect coculture system, only the HOBs on PCL-rod nHA films up-regulated the gene expression of Runx2, bone sialoprotein, and osteocalcin of ASCs. Additionally, the HOBs on PCL-rod nHA films showed significant up-regulation of bone morphogenic protein 2 gene and protein expression and induced highest phosphorylated Smad1/5 protein level in ASCs. Treatment of the coculture medium with bone morphogenic protein 2 inhibitor (Noggin) largely abolished the osteogenic differentiation of the ASCs induced by the HOBs on PCL-rod nHA films. In conclusion, HOBs can not only best display their osteoblastic phenotype by culturing on PCL-rod nHA films but also render an optimal osteogenic niche for the differentiation of stem cells.

Fat tissue morphology of long-term sex steroid deficiency and estrogen treatment in female rats

After long-term estradiol deficiency, female rats displayed body mass gain accompanied by an increase in the size of adipocytes, an increase in hyperglycemia, and a decrease in insulinemia. The effects were reversed by daily estradiol treatment. Adiposity was suggested by the increased vascular endothelial growth factor expression in castrated rats, whereas the proliferative effect of estradiol was suggested by the increased fibronectin expression in treated rats.

Stem cells from adipose tissue

This is a review of the growing scientific interest in the developmental plasticity and therapeutic potential of stromal cells isolated from adipose tissue. Adipose-derived stem/stromal cells (ASCs) are multipotent somatic stem cells that are abundant in fat tissue. It has been shown that ASCs can differentiate into several lineages, including adipose cells, chondrocytes, osteoblasts, neuronal cells, endothelial cells, and cardiomyocytes. At the same time, adipose tissue can be harvested by a minimally invasive procedure, which makes it a promising source of adult stem cells. Therefore, it is believed that ASCs may become an alternative to the currently available adult stem cells (e.g. bone marrow stromal cells) for potential use in regenerative medicine. In this review, we present the basic information about the field of adipose-derived stem cells and their potential use in various applications.