Development of extracellular matrices mimicking stepwise adipogenesis of mesenchymal stem cells

Chiral Cell Nanomechanics Originated in Clockwise/Counterclockwise Biofunctional Microarrays to Govern the Nuclear Mechanotransduction of Mesenchymal Stem Cells

Cell chirality is extremely important for the evolution of cell morphogenesis to manipulate cell performance due to left-right asymmetry. Although chiral micro- and nanoscale biomaterials have been developed to regulate cell functions, how cell chirality affects cell nanomechanics to command nuclear mechanotransduction was ambiguous. In this study, chiral engineered microcircle arrays were prepared by photosensitive cross-linking synthesis on cell culture plates to control the clockwise/counterclockwise geometric topology of stem cells. Asymmetric focal adhesion and cytoskeleton structures could induce chiral cell nanomechanics measured by atomic force microscopy (AFM) nanoindentation in left-/right-handed stem cells. Cell nanomechanics could be enhanced when the construction of mature focal adhesion and the assembly of actin and myosin cytoskeletons were well organized in chiral engineered stem cells. Curvature angles had a negative effect on cell nanomechanics, while cell chirality did not change cytoskeletal mechanics. The biased cytoskeleton tension would engender different nuclear mechanotransductions by yes-associated protein (YAP) evaluation. The chiral stimuli were delivered into the nuclei to oversee nuclear behaviors. A strong cell modulus could activate high nuclear DNA synthesis activity by mechanotransduction. The results will bring the possibility of understanding the interplay of chiral cell nanomechanics and mechanotransduction in nanomedicines and biomaterials.

Multilineage Differentiation Potential of Equine Adipose-Derived Stromal/Stem Cells from Different Sources

The investigation of multipotent stem/stromal cells (MSCs) in vitro represents an important basis for translational studies in large animal models. The study's aim was to examine and compare clinically relevant in vitro properties of equine MSCs, which were isolated from abdominal (abd), retrobulbar (rb) and subcutaneous (sc) adipose tissue by collagenase digestion (ASCs-_SVF) and an explant technique (ASCs-_EXP). Firstly, we examined proliferation and trilineage differentiation and, secondly, the cardiomyogenic differentiation potential using activin A, bone morphogenetic protein-4 and Dickkopf-1. Fibroblast-like, plastic-adherent ASCs-_SVF and ASCs-_EXP were obtained from all sources. The proliferation and chondrogenic differentiation potential did not differ significantly between the isolation methods and localizations. However, abd-ASCs-_EXP showed the highest adipogenic differentiation potential compared to rb- and sc-ASCs-_EXP on day 7 and abd-ASCs-_SVF a higher adipogenic potential compared to abd-ASCs-_EXP on day 14. Osteogenic differentiation potential was comparable at day 14, but by day 21, abd-ASCs-_EXP demonstrated a higher osteogenic potential compared to abd-ASCs-_SVF and rb-ASCs-_EXP. Cardiomyogenic differentiation could not be achieved. This study provides insight into the proliferation and multilineage differentiation potential of equine ASCs and is expected to provide a basis for future preclinical and clinical studies in horses.

The extracellular matrix of human bone marrow adipocytes and glucose concentration differentially alter mineralization quality without impairing osteoblastogenesis

Bone marrow adipocytes (BMAds) accrue in various states of osteoporosis and interfere with bone remodeling through the secretion of various factors. However, involvement of the extracellular matrix (ECM) produced by BMAds in the impairment of bone marrow mesenchymal stromal cell (BM-MSC) osteoblastogenesis has received little attention. In type 2 diabetes (T2D), skeletal fragility is associated with several changes in bone quality that are incompletely understood, and BMAd quantity increases in relationship to poor glycemic control. Considering their altered phenotype in this pathophysiological context, we aimed to determine the contribution of the ECM of mature BMAds to osteoblastogenesis and mineralization quality in the context of chronic hyperglycemia.

Human BM-MSCs were differentiated for 21 days in adipogenic medium containing either a normoglycemic (LG, 5.5 mM) or a high glucose concentration (HG, 25 mM). The ECM laid down by BMAds were devitalized through cell removal to examine their impact on the proliferation and differentiation of BM-MSCs toward osteoblastogenesis in LG and HG conditions. Compared to control plates, both adipocyte ECMs promoted cell adhesion and proliferation. As shown by the unmodified RUNX2 and osteocalcin mRNA levels, BM-MSC commitment in osteoblastogenesis was hampered by neither the hyperglycemic condition nor the adipocyte matrices. However, adipocyte ECMs or HG condition altered the mineralization phase with perturbed expression levels of type 1 collagen, MGP and osteopontin. Despite higher ALP activity, mineralization levels per cell were decreased for osteoblasts grown on adipocyte ECMs compared to controls. Raman spectrometry revealed that culturing on adipocyte matrices specifically prevents type-B carbonate substitution and favors collagen crosslinking, in contrast to exposure to HG concentration alone. Moreover, the mineral to organic ratio was disrupted according to the presence of adipocyte ECM and the glucose concentration used for adipocyte or osteoblast culture. HG concentration and adipocyte ECM lead to different defects in mineralization quality, recapitulating contradictory changes reported in T2D osteoporosis.

Our study shows that ECMs from BMAds do not impair osteoblastogenesis but alter both the quantity and quality of mineralization partly in a glucose concentration-dependent manner. This finding sheds light on the involvement of BMAds, which should be considered in the compromised bone quality of T2D and osteoporosis patients more generally.

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Glucose level alters the Extracellular Matrix composition of Bone Marrow adipocytes.

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Osteoblastogenesis on adipocyte ECMs is unaltered but produced less mineral amount.

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The quality of the mineral is altered differently by adipocyte ECMs or glucose levels.

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The presence of BM adipocytes should be valued in damaged osteoporosis bone quality.

The synergistic effect of physicochemical in vitro microenvironment modulators in human bone marrow stem cell cultures

Modern bioengineering utilises biomimetic cell culture approaches to control cell fate during in vitro expansion. In this spirit, herein we assessed the influence of bidirectional surface topography, substrate rigidity, collagen type I coating and macromolecular crowding (MMC) in human bone marrow stem cell cultures. In the absence of MMC, surface topography was a strong modulator of cell morphology. MMC significantly increased extracellular matrix deposition, albeit in a globular manner, independently of the surface topography, substrate rigidity and collagen type I coating. Collagen type I coating significantly increased cell metabolic activity and none of the assessed parameters affected cell viability. At day 14, in the absence of MMC, none of the assessed genes was affected by surface topography, substrate rigidity and collagen type I coating, whilst in the presence of MMC, in general, collagen type I α1 chain, tenascin C, osteonectin, bone sialoprotein, aggrecan, cartilage oligomeric protein and runt-related transcription factor were downregulated. Interestingly, in the presence of the MMC, the 1000 kPa grooved substrate without collagen type I coating upregulated aggrecan, cartilage oligomeric protein, scleraxis homolog A, tenomodulin and thrombospondin 4, indicative of tenogenic differentiation. This study further supports the notion for multifactorial bioengineering to control cell fate in culture.

Recent Developments in Extracellular Matrix Remodeling for Fat Grafting

Remodeling of the extracellular matrix (ECM), which provides structural and biochemical support for surrounding cells, is vital for adipose tissue regeneration after autologous fat grafting. Rapid and high-quality ECM remodeling can improve the retention rate after fat grafting by promoting neovascularization, regulating stem cells differentiation, and suppressing chronic inflammation. The degradation and deposition of ECM are regulated by various factors, including hypoxia, blood supply, inflammation, and stem cells. By contrast, ECM remodeling alters these regulatory factors, resulting in a dynamic relationship between them. Although researchers have attempted to identify the cellular sources of factors associated with tissue regeneration and regulation of the microenvironment, the factors and mechanisms that affect adipose tissue ECM remodeling remain incompletely understood. This review describes the process of adipose ECM remodeling after grafting and summarizes the factors that affect ECM reconstruction. Also, this review provides an overview of the clinical methods to avoid poor ECM remodeling. These findings may provide new ideas for improving the retention of adipose tissue after fat transplantation.

Development of a Biomimetic Hydrogel Based on Predifferentiated Mesenchymal Stem-Cell-Derived ECM for Cartilage Tissue Engineering

The use of decellularized extracellular matrix (dECM) as a biomaterial has been an important step forward for the development of functional tissue constructs. In addition to tissues and organs, cell cultures are gaining a lot of attention as an alternative source of dECM. In this work, a novel biomimetic hydrogel is developed based on dECM obtained from mesenchymal stem cells (mdECM) for cartilage tissue engineering. To this end, cells are seeded under specific culture conditions to generate an early chondrogenic extracellular matrix (ECM) providing cues and elements necessary for cartilage development. The composition is determined by quantitative, histological, and mass spectrometry techniques. Moreover, the decellularization process is evaluated by measuring the DNA content and compositional analyses, and the hydrogel is formulated at different concentrations (3% and 6% w/v). Results show that mdECM derived hydrogels possess excellent biocompatibility and suitable physicochemical and mechanical properties for their injectability. Furthermore, it is evidenced that this hydrogel is able to induce chondrogenesis of mesenchymal stem cells (MSCs) without supplemental factors and, furthermore, to form hyaline cartilage-like tissue after in vivo implantation. These findings demonstrate for the first time the potential of this hydrogel based on mdECM for applications in cartilage repair and regeneration.

Organ-specific ECM arrays for investigating Cell-ECM interactions during stem cell differentiation

Pluripotent stem cells are promising source of cells for tissue engineering, regenerative medicine and drug discovery applications. The process of stem cell differentiation is regulated by multi-parametric cues from the surrounding microenvironment, one of the critical one being cell interaction with extracellular matrix (ECM). The ECM is a complex tissue-specific structure which are important physiological regulators of stem cell function and fate. Recapitulating this native ECM microenvironment niche is best facilitated by decellularized tissue/ organ derived ECM, which can faithfully reproduce the physiological environment with high fidelity to in vivo condition and promote tissue-specific cellular development and maturation. Recognizing the need for organ specific ECM in a 3D culture environment in driving phenotypic differentiation and maturation of hPSCs, we fabricated an ECM array platform using native-mimicry ECM from decellularized organs (namely pancreas, liver and heart), which allows cell-ECM interactions in both 2D and 3D configuration. The ECM array was integrated with rapid quantitative imaging for a systematic investigation of matrix protein profiles and sensitive measurement of cell-ECM interaction during hPSC differentiation. We tested our platform by elucidating the role of the three different organ-specific ECM in supporting induced pancreatic differentiation of hPSCs. While the focus of this report is on pancreatic differentiation, the developed platform is versatile to be applied to characterize any lineage specific differentiation.

ECM scaffolds mimicking extracellular matrices of endochondral ossification for the regulation of mesenchymal stem cell differentiation

Endochondral ossification (ECO) is an important process of bone tissue development. During ECO, extracellular matrices (ECMs) are essential factors to control cell functions and induce bone regeneration. However, the exact role of ECO ECMs on stem cell differentiation remains elusive. In this study, ECM scaffolds were prepared to mimic the ECO-related ECM microenvironments and their effects on stem cell differentiation were compared. Four types of ECM scaffolds mimicking the ECMs of stem cells (SC), chondrogenic (CH), hypertrophic (HY) and osteogenic (OS) stages were prepared by controlling differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) at different stages. Composition of the ECM scaffolds was dependent on the differentiation stage of MSCs. They showed different influence on osteogenic differentiation of MSCs. HY ECM scaffold had the most promotive effect on osteogenic differentiation of MSCs. CH ECM and OS ECM scaffolds showed moderate effect, while SC ECM scaffold had the lowest effect on osteogenic differentiation of MSCs. Their effects on chondrogenic or adipogenic differentiation were not significantly different. The results suggested that the engineered HY ECM scaffold had superior effect for osteogenic differentiation of MSCs. Statement of significance ECM scaffolds mimicking endochondral ossification-related ECM microenvironments are pivotal for elucidation of their roles in regulation of stem cell functions and bone tissue regeneration. This study offers a method to prepare ECM scaffolds that mimic the ECMs from cells at hypertrophic, osteogenic, chondrogenic and stem cell stages. Their composition and impacts on osteogenic differentiation of MSCs were compared. The hypertrophic ECM scaffold had the highest promotive effect on osteogenic differentiation of MSCs. The results advance our understanding about the role of ECO ECMs in regulation of stem cell functions and provide perspective for bone defect repair strategies.

Re-engineered cell-derived extracellular matrix as a new approach to clarify the role of native ECM

An extracellular matrix (ECM) has both biochemical and mechanophysical characteristics obtained from multiple components, which provides cells a dynamic microenvironment. During reciprocal interactions with ECM, the cells actively remodel the matrix, including synthesis, degradation, and chemical modification, which play a pivotal role in various biological events such as disease progression or tissue developmental processes. Since a cell-derived decellularized ECM (cdECM) holds in vivo-like compositional heterogeneity and interconnected fibrillary architecture, it has received much attention as a promising tool for developing more physiological in vitro model systems. Despite these advantages, the cdECM has obvious limitations to mimic versatile ECMs precisely, suggesting the need for improved in vitro modeling to clarify the functions of native ECM. Recent studies propose to tailor the cdECM via biochemically, biomechanically, or incorporation with other systems as a new approach to address the limitations. In this chapter, we summarize the studies that re-engineered the cdECM to examine the features of native ECM in-depth and to increase physiological relevancy.

Decellularized extracellular matrices derived from cultured cells at stepwise myogenic stages for the regulation of myotube formation

The regulation of stem cell differentiation is key for muscle tissue engineering and regenerative medicine. To this end, various substrates mimicking the native extracellular matrix (ECM) have been developed with consideration of the mechanical, topological, and biochemical properties. However, mimicking the biochemical properties of the native ECM is difficult due to its compositional complexity. To develop substrates that mimic the native ECM and its biochemical properties, decellularization is typically used. Here, substrates mimicking the native ECM at each myogenic stage are prepared as stepwise myogenesis-mimicking matrices via the in vitro myogenic culture of C2C12 myoblasts and decellularization. Cells adhered to the stepwise myogenesis-mimicking matrices at similar levels. However, the matrices derived from cells at the myogenic early stage suppressed cell growth and promoted myogenesis. This promotion of myogenesis was potentially due to the suppression of the activation of endogenous BMP signaling following the suppression of the expression of the myogenic-inhibitory factors, Id2 and Id3. Our stepwise myogenesis-mimicking matrices will be suitable ECM models for basic biological research and myogenesis of stem cells. Further, these matrices will provide insights that improve the efficacy of decellularized ECM for muscle repair.

Stepwise Adipogenesis of Decellularized Cellular Extracellular Matrix Regulates Adipose Tissue-Derived Stem Cell Migration and Differentiation

Microenvironmental factors can modulate the cellular status of adipose tissue-derived stem cells (ASCs). In response to microenvironmental changes, cells can remodel extracellular matrix (ECM) proteins, which play an important role in regulating cell behaviors. During adipogenic differentiation, ECM components secreted from ASCs remodel dramatically. To evaluate the role of stepwise adipogenesis-induced cellular secretion of ECM on the behavior of ASCs, we cultured ASCs in growth and adipogenic media, and ECM secreted from cells was characterized and decellularized. The ASCs were then reseeded on decellularized ECM (d-ECM) to determine the regulatory effects of ECM on cellular behaviors. During adipogenesis, cell-secreted ECM underwent remodeling characterized by conversion from fibronectin-rich ECM to laminin-rich ECM. The cellular status of ASCs was tested after reseeding on decellularized ECM. When reseeded on growth d-ECM, ASCs exhibited greater migration ability. In contrast, ASCs seeded on adipogenic d-ECM underwent adipogenic differentiation. In addition, integrin subunit αv and integrins α6 and α7 were detected at significantly greater levels in ASCs cultured on growth and adipogenic d-ECM, respectively, suggesting that integrins play an important role in ASC migration and adipogenesis. This study demonstrated that stepwise adipogenesis-induced ECM production plays an important role in ASC migration and differentiation. In addition, this study provided a strategy to achieve precise regulation of stem cell function in adipose tissue engineering.

Human Adipose-Derived Stem Cell Secreted Extracellular Matrix Incorporated into Electrospun Poly(Lactic-co-Glycolic Acid) Nanofibrous Dressing for Enhancing Wound Healing

Wound dressing, which prevents dehydration and provides a physical barrier against infection to wound beds, can improve wound healing. The interactions between extracellular matrix (ECM) and growth factors is critical to the healing process. Electrospun nanofibers are promising templates for wound dressings due to the structure similarity to ECM of skin. Otherwise, the ECM secreted by human adipose-derived stem cells (hASCs) is rich in growth factors known to enhance wound healing. Accordingly, we propose that the PLGA nanofibrous template incorporated with hASCs-secreted ECM may enhance wound healing. In this study, PLGA nanofibrous matrixes with an aligned or a random structure were prepared by electrospinning. Human ASCs cultured on the aligned matrix had a better viability and produced a larger amount of ECM relative to that of random one. After 7 days' cultivation, the hASCs on aligned PLGA substrates underwent decellularization to fabricate cECM/PLGA dressings. By using immunohistochemical staining against F-actin and cell nucleus, the removal of cellular components was verified. However, the type I collagen and laminin were well preserved on the cECM/PLGA nanofibrous matrixes. In addition, this substrate was hydrophilic, with appropriate mechanical strength to act as a wound dressing. The L929 fibroblasts had good activity, survival and proliferation on the cECM/PLGA meshes. In addition, the cECM/PLGA nanofibrous dressings improved the wound healing of surgically created full-thickness skin excision in a mouse model. This hASCs-secreted ECM incorporated into electrospun PLGA nanofibrous could be a promising dressing for enhancing wound healing.

PLGA–collagen–ECM hybrid scaffolds functionalized with biomimetic extracellular matrices secreted by mesenchymal stem cells during stepwise osteogenesis-co-adipogenesis

Development of an in vitro 3D model that reflects the dynamic remodeling of ECMs during simultaneous osteogenesis and adipogenesis of hMSCs.

Nanoengineered, cell-derived extracellular matrix influences ECM-related gene expression of mesenchymal stem cells

Background

Human mesenchymal stem cells (hMSCs) are, due to their pluripotency, useful sources of cells for stem cell therapy and tissue regeneration. The phenotypes of hMSCs are strongly influenced by their microenvironment, in particular the extracellular matrix (ECM), the composition and structure of which are important in regulating stem cell fate. In reciprocal manner, the properties of ECM are remodeled by the hMSCs, but the mechanism involved in ECM remodeling by hMSCs under topographical stimulus is unclear. In this study, we therefore examined the effect of nanotopography on the expression of ECM proteins by hMSCs by analyzing the quantity and structure of the ECM on a nanogrooved surface.

Methods

To develop the nanoengineered, hMSC-derived ECM, we fabricated the nanogrooves on a coverglass using a UV-curable polyurethane acrylate (PUA). Then, hMSCs were cultivated on the nanogrooves, and the cells at the full confluency were decellularized. To analyze the effect of nanotopography on the hMSCs, the hMSCs were re-seeded on the nanoengineered, hMSC-derived ECM.

Results

hMSCs cultured within the nano-engineered hMSC-derived ECM sheet showed a different pattern of expression of ECM proteins from those cultured on ECM-free, nanogrooved surface. Moreover, hMSCs on the nano-engineered ECM sheet had a shorter vinculin length and were less well-aligned than those on the other surface. In addition, the expression pattern of ECM-related genes by hMSCs on the nanoengineered ECM sheet was altered. Interestingly, the expression of genes for osteogenesis-related ECM proteins was downregulated, while that of genes for chondrogenesis-related ECM proteins was upregulated, on the nanoengineered ECM sheet.

Conclusions

The nanoengineered ECM influenced the phenotypic features of hMSCs, and that hMSCs can remodel their ECM microenvironment in the presence of a nanostructured ECM to guide differentiation into a specific lineage.

Electronic supplementary material

The online version of this article (10.1186/s40824-018-0141-y) contains supplementary material, which is available to authorized users.

Recellularization of decellularized adipose tissue-derived stem cells: role of the cell-secreted extracellular matrix in cellular differentiation

Adipose-derived stem cells (ASCs) are found in a location within the adipose tissue known as the stem cell niche. The ASCs in the niche are maintained in the quiescent state, and upon exposure to various microenvironmental triggers are prompted to undergo proliferation or differentiation. These microenvironmental triggers also modulate the extracellular matrix (ECM), which interacts with the cells through the cytoskeleton and induces downstream events inside the cells that bring about a change in cell behaviour. In response to these changes, the cells remodel the ECM, which will differ according to the type of tissue being formed by the cells. As the ECM itself plays an important role in the regulation of cellular differentiation, this study aims to explore the role of the cell-secreted ECM at various stages of differentiation of stem cells in triggering the differentiation of ASCs. To this end, the ASCs cultured in proliferation, osteogenic and adipogenic media were decellularized and the secreted ECM was characterized. Overall, it was found that osteo-differentiated ASCs produced higher amounts of collagen and glycosaminoglycans (GAG) compared to the undifferentiated and adipo-differentiated ASCs. The two types of differentiated ECMs were subsequently shown to trigger initial but not terminal differentiation of ASCs into osteo- and adipo-lineages respectively, as indicated by the upregulation of lineage specific markers. In addition, integrin subunits alpha (α) 6 and integrin beta (β) 1 were found to be produced by ASCs cultured on cell-secreted ECM-coated substrates, suggesting that the integrins α6 and β1 play an instrumental role in cell-ECM interactions. Taken together, this study demonstrates the importance of the ECM in cellular fate decisions and how ECM-coated substrates can potentially be used for various tissue engineering applications.

Cell-Sheet-Derived ECM Coatings and Their Effects on BMSCs Responses

Extracellular matrix (ECM) provides a dynamic and complex environment to determine the fate of stem cells. In this work, light harvested cell sheets were treated with paraformaldehyde or ethanol, which eventually become ECM. Such ECM was then immobilized on titanium substrates via polydopamine chemistry. Their effects on bone marrow mesenchymal stromal cells (BMSCs) behaviors were investigated. It was found that paraformaldehyde-treated ECM coating (PT-ECM) showed a well-maintained microstructure, whereas that of ethanol-treated (ET-ECM) was completely changed. As a result, different amide structures and distributions of ECM components, such as laminin and collagen I, were exhibited. Alkaline phosphatase activity, osteocalcin secretion, related gene expression, and mineral deposition were evaluated for BMSCs cultured on both ECM coatings. PT-ECM was demonstrated to promote osteogenic differentiation much more efficiently than that of ET-ECM. That is ascribed to the preservation of native ECM milieu of PT-ECM. Such ECM acquirement and immobilization method could establish surfaces being able to direct stem cell responses on various materials. That shows promising potential in bone tissue engineering and other related biomedical applications.

Preparation of Cell-Derived Decellularized Matrices Mimicking Native ECM During the Osteogenesis and Adipogenesis of Mesenchymal Stem Cells

The extracellular matrix (ECM) is an important extracellular microenvironmental factor that regulates stem cell differentiation. The ECM is remodeled according to stem cell differentiation progression to precisely regulate the differentiation. Thus, it is expected that the matrices mimicking native ECM surrounding differentiating cells at each differentiation stage provide a favorable microenvironment to promote stem cell differentiation. However, it is difficult to prepare matrices mimicking native ECM using chemical methods because the ECM has a complicated composition. The decellularization technique is useful to prepare such matrices. In this chapter, we described the protocol to prepare matrices mimicking native ECM surrounding cells that are differentiating from mesenchymal stem cells to either osteoblasts or adipocytes via stem cell differentiation culture and a detergent- and nuclease-based decellularization technique.

Long-term G1 cell cycle arrest in cervical cancer cells induced by co-immobilized TNF-α plus IFN-γ polymeric drugs

A realistic control of cell cycle arrest is an attractive goal for the development of new effective anti-cancer drugs. Any clinical application of an effective anti-cancer drug necessarily relies on the understanding of cellular interaction mechanisms. In the present study, we prepared a co-immobilized TNF-α plus IFN-γ biomaterial, which showed a significant inhibition effect on cervical cancer cell growth, as demonstrated by a series of structural and cellular characterizations. We found that co-immobilized TNF-α plus IFN-α induced a long-term G₁ phase cell cycle arrest in HeLa, SiHa, and CaSki cells, respectively. More surprisingly, the expression level of the p27 protein decreased, even when p27 mRNA was highly expressed. In addition, gene-chip results and microarray analysis showed that p57 may be downstream from p27, which acts as a direct regulator of the long-term G₁ cell cycle arrest in these cells, leaving no escape for cervical cancer cells. Finally, we also investigated the anti-tumor mechanism of co-immobilized TNF-α plus IFN-γin vivo, using a nude mice animal model. To sum up, our findings suggested that the co-immobilized TNF-α plus IFN-γ can induce a long-term cell cycle arrest in cancer, thus serving as a very efficient tool for treating cervical cancer.

Induction of Chondrogenic Differentiation of Human Mesenchymal Stem Cells by Biomimetic Gold Nanoparticles with Tunable RGD Density

Nanostructured materials have drawn a broad attention for their applications in biomedical fields. Ligand-modified nanomaterials can well mimic the dynamic extracellular matrix (ECM) microenvironments to regulate cell functions and fates. Herein, ECM mimetic gold nanoparticles (Au NPs) with tunable surface arginine-glycine-aspartate (RGD) density are designed and synthesized to induce the chondrogenic differentiation of human mesenchymal stem cells (hMSCs). The biomimetic Au NPs with an average size of 40 nm shows good biocompatibility without affecting the cell proliferation in the studied concentration range. The RGD motifs on Au NPs surface facilitate cellular uptake of NPs into monolayer hMSCs through integrin-mediated endocytosis. The biomimetic NPs have a promotive effect on cartilaginous matrix production and marker gene expression in cell pellet culture, especially for the biomimetic Au NPs with high surface RGD density. This study provides a novel strategy for fabricating biomimetic NPs to regulate cell differentiation, which holds great potentials in tissue engineering and biomedical applications.

Extracellular matrix powder from cultured cartilage-like tissue as cell carrier for cartilage repair

Cartilage extracellular matrix (ECM) is a promising material for cartilage repair because of its bioactivity. However, the animal source of ECM unavoidably increases the risk of pathogen infection and the variability of product quality. In this study, we utilized a novel 3D culture method to prepare a new type of artificial decellularized matrix powder (DEMP) for the development of injectable, bioactive, biodegradable cell carriers for cartilage tissue engineering. This culture method combined hanging drop culture with suspension culture method, and was very efficient to produce cartilage-like tissue (CLT). By this method, an initial 2.3 × 10⁶ chondrocyte generated as much as 58.22 mg wet weight CLT at two weeks, which proved to contain abundant glycoaminoglycans (GAGs), type II collagen, and BMP-2 and TGF-β1 growth factors by staining techniques and biochemical analysis. Subsequently, the two-week-old CLT was decellularized to prepare the artificial DEMP. In an in vitro study, it was found that MSCs cultured on DEMP differentiated to chondrocytes very well and secreted rich GAGs and type II collagen at three weeks even without exogenous TGF-β1. The in vivo study demonstrated that the DEMP not only facilitated regeneration of hyaline cartilage, which was implied by the intense staining of GAGs and type II collagen in rabbit subchondral defects at 1 month, but also benefited the regeneration of subchondral bone (bone ingrowth at 1 month: 48.22%) as shown in micro-CT data. Collectively, these results suggest that the artificial DEMP prepared by this culture method holds great potential as a novel ECM material for cartilage repair.

3D-printed porous titanium changed femoral head repair growth patterns: osteogenesis and vascularisation in porous titanium

Osteonecrosis of the femoral head (ONFH) is a major cause of morbidity, and total hip arthroplasty is both traumatic and expensive. Here, we created a gelatine scaffold embedded in uniquely shaped, 3D-printed porous titanium parts, which could attract and promote the proliferation of osteoblasts as well as bone regeneration, as the extracellular matrix (ECM) does in vivo. Interestingly, after hybridisation with platelets, the scaffold exhibited a low yet considerable rate of stable, safe and long-term growth factor release. Additionally, a novel ONFH model was constructed and verified. Scaffolds implanted in this model were found to accelerate bone repair. In conclusion, our scaffold successfully simulates the ECM and considerably accelerates bone regeneration, in which platelets play an indispensable role. We believe that platelets should be emphasised as carriers that may be employed to transport drugs, cytokines and other small molecules to target locations in vivo. In addition, this novel scaffold is a useful material for treating ONFH. An overview of the novel scaffold mimicking the extracellular environment in bone repair. a and b: A gelatine scaffold was cross-linked and freeze-dried within 3D-printed porous titanium. c: Platelets were coated onto the gelatine microscaffold after freeze-drying platelet-rich plasma. d: The microscaffold supported the migration of cells into the titanium pores and their subsequent growth, while the platelets slowly released cell factors, exerting bioactivity.

Cultured cell-derived decellularized matrices: a review towards the next decade

Summary of recent progress in cell-derived decellularized matrices preparation and application, with perspectives towards the next decade.

Sub-10 nm gold nanoparticles promote adipogenesis and inhibit osteogenesis of mesenchymal stem cells

Sub-10 nm Au NPs with an average size of 4 nm (Au4-mPEG NPs) had a promotive effect on the adipogenic differentiation and an inhibitive effect on the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) due to the highly induced ROS level.

Decellularized matrices as in vitro models of extracellular matrix in tumor tissues at different malignant levels: Mechanism of 5-fluorouracil resistance in colorectal tumor cells

Chemoresistance is a major barrier for tumor chemotherapy. It is well-known that chemoresistance increases with tumor progression. Chemoresistance is altered by both genetic mutations and the alteration of extracellular microenvironment. Particularly, the extracellular matrix (ECM) is remodeled during tumor progression. Therefore, ECM remodeling is expected to cause the acquisition of chemoresistance in highly malignant tumor tissue. Here, we prepared cultured cell-derived decellularized matrices that mimic native ECM in tumor tissues at different stages of malignancy, and 5-fluorouracil (5-FU) resistance was compared among these matrices. 5-FU resistance of colorectal tumor cells increased on the matrices derived from highly malignant tumor HT-29 cells, although the resistance did not increase on the matrices derived from low malignant tumor SW480 cells and normal CCD-841-CoN cells. The resistance on HT-29 cell-derived matrices increased through the activation of Akt and the upregulation of ABCB1 and ABCC1 without cell growth promotion, suggesting that ECM remodeling plays important roles in the acquisition of chemoresistance during tumor progression. It is expected that our decellularized matrices, or "staged tumorigenesis-mimicking matrices", will become preferred cell culture substrates for in vitro analysis of comprehensive ECM roles in chemoresistance and the screening and pharmacokinetic analysis of anti-cancer drugs.

3D Culture of Chondrocytes in Gelatin Hydrogels with Different Stiffness

Gelatin hydrogels can mimic the microenvironments of natural tissues and encapsulate cells homogeneously, which makes them attractive for cartilage tissue engineering. Both the mechanical and biochemical properties of hydrogels can affect the phenotype of chondrocytes. However, the influence of each property on chondrocyte phenotype is unclear due to the difficulty in separating the roles of these properties. In this study, we aimed to study the influence of hydrogel stiffness on chondrocyte phenotype while excluding the role of biochemical factors, such as adhesion site density in the hydrogels. By altering the degree of methacryloyl functionalization, gelatin hydrogels with different stiffnesses of 3.8, 17.1, and 29.9 kPa Young's modulus were prepared from the same concentration of gelatin methacryloyl (GelMA) macromers. Bovine articular chondrocytes were encapsulated in the hydrogels and cultured for 14 days. The influence of hydrogel stiffness on the cell behaviors including cell viability, cell morphology, and maintenance of chondrogenic phenotype was evaluated. GelMA hydrogels with high stiffness (29.9 kPa) showed the best results on maintaining chondrogenic phenotype. These results will be useful for the design and preparation of scaffolds for cartilage tissue engineering.

Matrices secreted during simultaneous osteogenesis and adipogenesis of mesenchymal stem cells affect stem cells differentiation

The extracellular matrix (ECM) plays a pivotal role in regulating stem cell functions. The ECM dynamically changes during tissue development. It remains a great challenge to mimic the dynamically changing ECM. In this study, we prepared novel types of extracellular matrices that could mimic the dynamic variation of extracellular matrices, which were derived from simultaneous osteogenesis and adipogenesis of human bone marrow-derived mesenchymal stem cells (MSCs). Four ECMs simultaneously mimicking early osteogenesis and early adipogenesis (EOEA), early osteogenesis and late adipogenesis (EOLA), late osteogenesis and early adipogenesis (LOEA), late osteogenesis and late adipogenesis (LOLA) were prepared. The stepwise osteogenesis-co-adipogenesis-mimicking matrices had different compositions and different effects on the osteogenic and adipogenic differentiation of MSCs. The matrices could provide very useful tools to investigate the interaction between ECM and stem cells and the role of ECM on stem cell differentiation.

STATEMENT OF SIGNIFICANCE

Extracellular matrices (ECMs) are dynamically remodeled to regulate stem cell functions during tissue development. Until now, mimicking the ECM variation during stem cell differentiation to single cell type has been reported. However, there is no report on simultaneous mimicking of stem cell differentiation to two types of cells. In this study, we prepared the mixture ECMs derived from simultaneous osteogenesis and adipogenesis of MSCs at different stages and found that they could regulate stem cell differentiation. The concept is new and the ECMs are novel. No such ECMs have been reported previously. The matrices will provide very useful tools to investigate the interaction between ECM and stem cells and the role of ECM on stem cell differentiation.

Hepatic differentiation of human pluripotent stem cells on human liver progenitor HepaRG-derived acellular matrix

Human hepatocytes are extensively needed in drug discovery and development. Stem cell-derived hepatocytes are expected to be an improved and continuous model of human liver to study drug candidates. Generation of endoderm-derived hepatocytes from human pluripotent stem cells (hPSCs), including human embryonic stem cells and induced pluripotent stem cells, is a complex, challenging process requiring specific signals from soluble factors and insoluble matrices at each developmental stage. In this study, we used human liver progenitor HepaRG-derived acellular matrix (ACM) as a hepatic progenitor-specific matrix to induce hepatic commitment of hPSC-derived definitive endoderm (DE) cells. The DE cells showed much better attachment to the HepaRG ACM than other matrices tested and then differentiated towards hepatic cells, which expressed hepatocyte-specific makers. We demonstrate that Matrigel overlay induced hepatocyte phenotype and inhibited biliary epithelial differentiation in two hPSC lines studied. In conclusion, our study demonstrates that the HepaRG ACM, a hepatic progenitor-specific matrix, plays an important role in the hepatic differentiation of hPSCs.

Advancing biomaterials of human origin for tissue engineering

Biomaterials have played an increasingly prominent role in the success of biomedical devices and in the development of tissue engineering, which seeks to unlock the regenerative potential innate to human tissues/organs in a state of deterioration and to restore or reestablish normal bodily function. Advances in our understanding of regenerative biomaterials and their roles in new tissue formation can potentially open a new frontier in the fast-growing field of regenerative medicine. Taking inspiration from the role and multi-component construction of native extracellular matrices (ECMs) for cell accommodation, the synthetic biomaterials produced today routinely incorporate biologically active components to define an artificial in vivo milieu with complex and dynamic interactions that foster and regulate stem cells, similar to the events occurring in a natural cellular microenvironment. The range and degree of biomaterial sophistication have also dramatically increased as more knowledge has accumulated through materials science, matrix biology and tissue engineering. However, achieving clinical translation and commercial success requires regenerative biomaterials to be not only efficacious and safe but also cost-effective and convenient for use and production. Utilizing biomaterials of human origin as building blocks for therapeutic purposes has provided a facilitated approach that closely mimics the critical aspects of natural tissue with regard to its physical and chemical properties for the orchestration of wound healing and tissue regeneration. In addition to directly using tissue transfers and transplants for repair, new applications of human-derived biomaterials are now focusing on the use of naturally occurring biomacromolecules, decellularized ECM scaffolds and autologous preparations rich in growth factors/non-expanded stem cells to either target acceleration/magnification of the body's own repair capacity or use nature's paradigms to create new tissues for restoration. In particular, there is increasing interest in separating ECMs into simplified functional domains and/or biopolymeric assemblies so that these components/constituents can be discretely exploited and manipulated for the production of bioscaffolds and new biomimetic biomaterials. Here, following an overview of tissue auto-/allo-transplantation, we discuss the recent trends and advances as well as the challenges and future directions in the evolution and application of human-derived biomaterials for reconstructive surgery and tissue engineering. In particular, we focus on an exploration of the structural, mechanical, biochemical and biological information present in native human tissue for bioengineering applications and to provide inspiration for the design of future biomaterials.

Decellularized Extracellular Matrix as an In Vitro Model to Study the Comprehensive Roles of the ECM in Stem Cell Differentiation

Stem cells are a promising cell source for regenerative medicine. Stem cell differentiation must be regulated for applications in regenerative medicine. Stem cells are surrounded by extracellular matrix (ECM) in vivo. The ECM is composed of many types of proteins and glycosaminoglycans that assemble into a complex structure. The assembly of ECM molecules influences stem cell differentiation through orchestrated intracellular signaling activated by many ECM molecules. Therefore, it is important to understand the comprehensive role of the ECM in stem cell differentiation as well as the functions of the individual ECM molecules. Decellularized ECM is a useful in vitro model for studying the comprehensive roles of ECM because it retains a native-like structure and composition. Decellularized ECM can be obtained from in vivo tissue ECM or ECM fabricated by cells cultured in vitro. It is important to select the correct decellularized ECM because each type has different properties. In this review, tissue-derived and cell-derived decellularized ECMs are compared as in vitro ECM models to examine the comprehensive roles of the ECM in stem cell differentiation. We also summarize recent studies using decellularized ECM to determine the comprehensive roles of the ECM in stem cell differentiation.

Perilipin+ embryonic preadipocytes actively proliferate along growing vasculatures for adipose expansion

Despite the growing interest in adipose tissue as a therapeutic target of metabolic diseases, the identity of adipocyte precursor cells (preadipocytes) and the formation of adipose tissue during embryonic development are still poorly understood. Here, we clarified the identity and dynamic processes of preadipocytes in mouse white adipose tissue during embryogenesis through direct examination, lineage tracing and culture systems. Surprisingly, we found that lipid-lacking but perilipin(+) or adiponectin(+) proliferating preadipocytes started to emerge at embryonic day 16.5, and these cells underwent active proliferation until birth. Moreover, these preadipocytes resided as clusters and were distributed along growing adipose vasculatures. Importantly, the embryonic preadipocytes exhibited considerable coexpression of stem cell markers, such as CD24, CD29 and PDGFRα, and a small portion of preadipocytes were derived from PDGFRβ(+) mural cells, in contrast to the adult preadipocytes present in the stromal vascular fraction. Further analyses with in vitro and ex vivo culture systems revealed a stepwise but dynamic regulation of preadipocyte formation and differentiation during prenatal adipogenesis. To conclude, we unraveled the identity and characteristics of embryonic preadipocytes, which are crucial for the formation and expansion of adipose tissue during embryogenesis.

Influence of stepwise chondrogenesis-mimicking 3D extracellular matrix on chondrogenic differentiation of mesenchymal stem cells

Extracellular matrix (ECM) has drawn a broad attention for preparation of tissue engineering scaffolds and stem cell study. ECM scaffolds stepwise mimicking development of tissues can provide useful models to investigate the interactions between stem cells and ECM during the process of tissue development. In this study, 3D stepwise chondrogenesis-mimicking ECM scaffolds were prepared from mesenchymal stem cells (MSCs) by controlling the stages of chondrogenic differentiation. ECM scaffolds mimicking the early stage and late stage of chondrogenesis were obtained when MSCs were cultured in the chondrogenic medium for 1 and 3 w, respectively. The ECM scaffolds had different compositions as shown by immunohistochemical analysis. Stem cell (SC)-ECM scaffold was rich in collagen I and biglycan. Early stage chondrogenesis-mimicking (CE)-ECM scaffold had moderate amount of collagen II and aggrecan while late stage chondrogenesis-mimicking (CL)-ECM scaffold were rich in collagen II and aggrecan. These three ECM scaffolds had different effects on chondrogenesis of MSCs. The CE-ECM scaffold facilitated chondrogenesis, however the CL-ECM scaffolds remarkably inhibited chondrogenesis of MSCs. These ECM scaffolds not only can provide new 3D ECM models to investigate the effects of ECM on MSCs functions, but also can be used as favorable ECM scaffolds for tissue engineering.

Biomaterials for in situ tissue regeneration: development and perspectives

Biomaterials are of fundamental importance to in situ tissue regeneration, which has emerged as a powerful method to treat tissue defects. The development and perspectives of biomaterials for in situ tissue regeneration were summarized.

Influence of surfaces modified with biomimetic extracellular matrices on adhesion and proliferation of mesenchymal stem cells and osteosarcoma cells

Preparation of surfaces modified with biomimetic extracellular matrices (ECMs) is important for investigation of the interaction between ECMs and cells. In the present study, surfaces modified with ECMs from normal somatic cells, stem cells and tumor cells were prepared by cell culture method. The ECMs derived from bone marrow-derived mesenchymal stem cells (MSCs), dermal fibroblasts (FBs), osteoblasts (OBs) and MG63 osteosarcoma cells were deposited on the surfaces of cell-culture polystyrene plates (TCPS). The ECMs from different cell types had different compositions. The effects of the ECM-deposited surfaces on the adhesion, spreading and proliferation of MSCs and MG63 human osteosarcoma cells were dependent on the type of both ECMs and cells. The surfaces deposited with ECMs from MSCs, FBs and OBs promoted cell adhesion more strongly than surfaces deposited with ECMs from MG63 cells and TCPS. Compared to TCPS, the ECM-deposited surfaces promoted proliferation of MSCs while they inhibited the proliferation of MG63 cells.

Powerful inner/outer controlled multi-target magnetic nanoparticle drug carrier prepared by liquid photo-immobilization

Nanomagnetic materials offer exciting avenues for advancing cancer therapies. Most researches have focused on efficient delivery of drugs in the body by incorporating various drug molecules onto the surface of nanomagnetic particles. The challenge is how to synthesize low toxic nanocarriers with multi-target drug loading. The cancer cell death mechanisms associated with those nanocarriers remain unclear either. Following the cell biology mechanisms, we develop a liquid photo-immobilization approach to attach doxorubicin, folic acid, tumor necrosis factor-α, and interferon-γ onto the oleic acid molecules coated Fe3O4 magnetic nanoparticles to prepare a kind of novel inner/outer controlled multi-target magnetic nanoparticle drug carrier. In this work, this approach is demonstrated by a variety of structural and biomedical characterizations, addressing the anti-cancer effects in vivo and in vitro on the HeLa, and it is highly efficient and powerful in treating cancer cells in a valuable programmed cell death mechanism for overcoming drug resistance.

Preparation of cylinder-shaped porous sponges of poly(L-lactic acid), poly(DL-lactic-co-glycolic acid), and poly(ε-caprolactone)

Design of mechanical skeletons of biodegradable synthetic polymers such as poly(L-lactic acid) (PLLA), poly(DL-lactic-co-glycolic acid) (PLGA), and poly(ε-caprolactone) (PCL) is important in the construction of the hybrid scaffolds of biodegradable synthetic polymers and naturally derived polymers such as collagen. In this study, cylinder-shaped PLLA, PLGA, and PCL sponges were prepared by the porogen leaching method using a cylinder model. The effects of polymer type, polymer fraction, cylinder height, pore size, and porosity on the mechanical properties of the cylinder-shape sponges were investigated. SEM observation showed that these cylinder-shaped sponges had evenly distributed bulk pore structures and the wall surfaces were less porous with a smaller pore size than the wall bulk pore structures. The porosity and pore size of the sponges could be controlled by the ratio and size of the porogen materials. The PLGA sponges showed superior mechanical properties than those of the PLLA and PCL sponges. Higher porosity resulted in an inferior mechanical strength. The pore size and sponge height also affected the mechanical properties. The results indicate that cylinder-shaped sponges can be tethered by choosing the appropriate polymers, size and ratio of porogen materials and dimension of sponges based on the purpose of the application.

Towards the generation of patient-specific patches for cardiac repair

Cardiovascular diseases represent the main cause of morbidity and mortality worldwide. Millions of people are affected by such diseases in the industrialized countries, with hundreds of thousands new cases diagnosed every year. Among cardiac diseases, heart failure is the most common end-stage pathology, leading to impaired cardiac output and cardiac performance as a result of the irreversible loss of contractile cardiomyocytes. Tissue engineering holds the promise to provide personalized solutions to the problem of cardiac muscle repair. Indeed, the identification of little reservoirs of stem and progenitor cells within every body district opened new perspectives to the setup of patient-specific protocols for cardiac diseases. Nonetheless, the results of the first pre-clinical and clinical trials in which adult stem/progenitor cells were adopted pointed at the route of delivery to the injured organ as well as at the cell source as the main issues for cardiac tissue engineers. In fact, when adult stem cells were directly injected into the myocardium or delivered through bloodstream to the heart, no or few cells could be found engrafted within host tissue few days after the administration. Renewed enthusiasm was generated by the techniques set up to enrich cardiomyocytes obtained by embryonic stem cells and by the recent disclosure of the protocols to obtain reprogrammed pluripotent cells or reprogrammed cardiomyocytes out of patients' own somatic cells. In this context, additional efforts to setup efficient systems to deliver stem cells to the injured site are required. The application of forefront technologies to fabricate synthetic and hybrid scaffolds to be employed as cell delivery systems and the acknowledgement that surface physical, mechanical, chemical properties can exert specific effects on stem cells per se prompted new enthusiasm in the field. In this respect, a cardiac-specific scaffold should be able to comply with cardiac muscle architecture, be deformable as to indulge and possibly sustain cardiac contraction. As expected, such a scaffold should favor stem cell electromechanical coupling with host tissue, while promoting the vascularization of the newly-formed tissue.

Stem cell culture using cell-derived substrates

There have been great efforts to develop cell culture systems using chemically-fixed cells or decellularized matrices to regulate stem cell functions.

Breast cancer cell behaviors on staged tumorigenesis-mimicking matrices derived from tumor cells at various malignant stages

Extracellular matrix (ECM) has been focused to understand tumor progression in addition to the genetic mutation of cancer cells. Here, we prepared "staged tumorigenesis-mimicking matrices" which mimic in vivo ECM in tumor tissue at each malignant stage to understand the roles of ECM in tumor progression. Breast tumor cells, MDA-MB-231 (invasive), MCF-7 (non-invasive), and MCF-10A (benign) cells, were cultured to form their own ECM beneath the cells and formed ECM was prepared as staged tumorigenesis-mimicking matrices by decellularization treatment. Cells showed weak attachment on the matrices derived from MDA-MB-231 cancer cells. The proliferations of MDA-MB-231 and MCF-7 was promoted on the matrices derived from MDA-MB-231 cancer cells whereas MCF-10A cell proliferation was not promoted. MCF-10A cell proliferation was promoted on the matrices derived from MCF-10A cells. Chemoresistance of MDA-MB-231 cells against 5-fluorouracil increased on only matrices derived from MDA-MB-231 cells. Our results showed that the cells showed different behaviors on staged tumorigenesis-mimicking matrices according to the malignancy of cell sources for ECM preparation. Therefore, staged tumorigenesis-mimicking matrices might be a useful in vitro ECM models to investigate the roles of ECM in tumor progression.

Effects of extracellular matrix proteins in chondrocyte-derived matrices on chondrocyte functions

Loss of cartilaginous phenotype during in vitro expansion culture of chondrocytes is a major barrier to the application of chondrocytes for tissue engineering. In previous study, we showed that dedifferentiation of chondrocytes during the passage culture was delayed by matrices formed by primary chondrocytes (P0-ECM). In this study, we investigated bovine chondrocyte functions when being cultured on isolated extracellular matrix (ECM) protein-coated substrata and P0-ECM. Low chondrocyte attachment was observed on aggrecan-coated substratum and P0-ECM. Cell proliferation on aggrecan- and type II collagen/aggrecan-coated substrata and P0-ECM was lower than that on the other ECM protein (type I collagen and type II collagen)-coated substrata. When chondrocytes were subcultured on aggrecan-coated substratum, decline of cartilaginous gene expression was delayed, which was similar to the cells subcultured on P0-ECM. These results indicate that aggrecan plays an important role in the regulation of chondrocyte functions and P0-ECM may be a good experimental control for investigating the role of each ECM protein in cartilage ECM.

Autocrine fibroblast growth factor 2-mediated interactions between human mesenchymal stem cells and the extracellular matrix under varying oxygen tension

Human mesenchymal stromal or stem cells (hMSCs) are being investigated for cell therapy in a wide range of diseases. MSCs are a potent source of trophic factors and actively remodel their immediate microenvironment through the secretion of bioactive factors in response to external stimuli such as oxygen tension. In this study, we examined the hypothesis that hypoxia influences hMSC properties in part through the regulation of extracellular milieu characterized by the extracellular matrix (ECM) matrices and the associated fibroblast growth factor-2 (FGF-2). The decellularized ECM matrices derived from hMSC culture under both hypoxic (e.g., 2% O(2)) and the standard culture (e.g., 20% O(2)) conditions have different binding capacities to the cell-secreted and exogenenous FGF-2. The reduced hMSC proliferation in the presence of FGF-2 inhibitor and the differential capacity of the decellularized ECM matrices in regulating hMSC osteogeneic and adipogenic differentiation suggest an important role of the endogenous FGF-2 in sustaining hMSC proliferation and regulating hMSC fate. Additionally, the combination of the ECM adhesion and hypoxic culture preserved hMSC viability under serum withdrawal. Together, the results suggest the synergistic effect of hypoxia and the ECM matrices in sustaining hMSC ex vivo expansion and preserving their multi-potentiality and viability under nutrient depletion. The results have important implication in optimizing hMSC expansion and delivery strategies to obtain hMSCs in sufficient quantity with required potency and to enhance survival and function upon transplantation.

Extracellular matrix aggregates from differentiating embryoid bodies as a scaffold to support ESC proliferation and differentiation

Embryonic stem cells (ESCs) have emerged as potential cell sources for tissue engineering and regeneration owing to its virtually unlimited replicative capacity and the potential to differentiate into a variety of cell types. Current differentiation strategies primarily involve various growth factor/inducer/repressor concoctions with less emphasis on the substrate. Developing biomaterials to promote stem cell proliferation and differentiation could aid in the realization of this goal. Extracellular matrix (ECM) components are important physiological regulators, and can provide cues to direct ESC expansion and differentiation. ECM undergoes constant remodeling with surrounding cells to accommodate specific developmental event. In this study, using ESC derived aggregates called embryoid bodies (EB) as a model, we characterized the biological nature of ECM in EB after exposure to different treatments: spontaneously differentiated and retinoic acid treated (denoted as SPT and RA, respectively). Next, we extracted this treatment-specific ECM by detergent decellularization methods (Triton X-100, DOC and SDS are compared). The resulting EB ECM scaffolds were seeded with undifferentiated ESCs using a novel cell seeding strategy, and the behavior of ESCs was studied. Our results showed that the optimized protocol efficiently removes cells while retaining crucial ECM and biochemical components. Decellularized ECM from SPT EB gave rise to a more favorable microenvironment for promoting ESC attachment, proliferation, and early differentiation, compared to native EB and decellularized ECM from RA EB. These findings suggest that various treatment conditions allow the formulation of unique ESC-ECM derived scaffolds to enhance ESC bioactivities, including proliferation and differentiation for tissue regeneration applications.

Modulation of BMP-2-induced chondrogenic versus osteogenic differentiation of human mesenchymal stem cells by cell-specific extracellular matrices

Bone morphogenetic protein-2 (BMP-2) is known to induce both osteogenic and chondrogenic commitment of human mesenchymal stem cells (hMSCs). However, factors influencing BMP-2-dependent chondrogenic and osteogenic differentiation have not been investigated. In this study, we demonstrated that extracellular microenvironments, in the form of cell-derived matrices, play important roles in determining the specific lineage commitment of hMSCs in the presence of BMP-2. Extracellular matrices (ECMs) derived from osteoblasts and chondrocytes were utilized to regulate cell differentiation. Osteogenic and chondrogenic differentiation of hMSCs cultured on the two different cell-derived ECMs were assessed by quantitative real-time-polymerase chain reaction, immunocytochemistry, and western blot analysis. To minimize the effects of the cell-adhesion proteins contained in serum on the ECMs, hMSCs were cultured in serum-free osteogenic or chondrogenic differentiation medium. Fibronectin-, collagen type I-, or collagen type II-coated substrates were utilized as ECM controls. The ECM specific to each cell type promoted lineage-specific commitment of hMSCs in the presence of BMP-2, that is, osteoblast- and chondrocyte-derived ECM promoted osteogenic and chondrogenic commitment, respectively. Therefore, cell-specific ECMs are capable of modulating the BMP-2-induced osteogenic and chondrogenic differentiation of hMSCs.