Center for Cellular and Molecular Engineering

Sun City Center, United States

Center for Cellular and Molecular Engineering

Sun City Center, United States
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Sun A.X.,University of Pittsburgh | Lin H.,Center for Cellular and Molecular Engineering | Fritch M.R.,University of Pittsburgh | Shen H.,CAS Suzhou Institute of Nano Technology and Nano Bionics | And 3 more authors.
Acta Biomaterialia | Year: 2016

Three-dimensional hydrogel constructs incorporated with live stem cells that support chondrogenic differentiation and maintenance offer a promising regenerative route towards addressing the limited self-repair capabilities of articular cartilage. In particular, hydrogel scaffolds that augment chondrogenesis and recapitulate the native physical properties of cartilage, such as compressive strength, can potentially be applied in point-of-care procedures. We report here the synthesis of two new materials, [poly-l-lactic acid/polyethylene glycol/poly-l-lactic acid] (PLLA-PEG 1000) and [poly-d,l-lactic acid/polyethylene glycol/poly-d,l-lactic acid] (PDLLA-PEG 1000), that are biodegradable, biocompatible (>80% viability post fabrication), and possess high, physiologically relevant mechanical strength (∼1500 to 1800kPa). This study examined the effects of physiologically relevant cell densities (4, 8, 20, and 50×106/mL) and hydrogel stiffnesses (∼150kPa to∼1500kPa Young's moduli) on chondrogenesis of human bone marrow stem cells incorporated in hydrogel constructs fabricated with these materials and a previously characterized PDLLA-PEG 4000. Results showed that 20×106 cells/mL, under a static culture condition, was the most efficient cell seeding density for extracellular matrix (ECM) production on the basis of hydroxyproline and glycosaminoglycan content. Interestingly, material stiffness did not significantly affect chondrogenesis, but rather material concentration was correlated to chondrogenesis with increasing levels at lower concentrations based on ECM production, chondrogenic gene expression, and histological analysis. These findings establish optimal cell densities for chondrogenesis within three-dimensional cell-incorporated hydrogels, inform hydrogel material development for cartilage tissue engineering, and demonstrate the efficacy and potential utility of PDLLA-PEG 1000 for point-of-care treatment of cartilage defects. Statement of Significance: Engineering cartilage with physiologically relevant mechanical properties for point-of-care applications represents a major challenge in orthopedics, given the generally low mechanical strengths of traditional hydrogels used in cartilage tissue engineering. In this study, we characterized a new material that possesses high mechanical strength similar to native cartilage, and determined the optimal cell density and scaffold stiffness to achieve the most efficient chondrogenic response from seeded human bone marrow stem cells. Results show robust chondrogenesis and strongly suggest the potential of this material to be applied clinically for point-of-care repair of cartilage defects. © 2017.

Boyette L.B.,U.S. National Institutes of Health | Boyette L.B.,Center for Cellular and Molecular Engineering | Boyette L.B.,McGowan Institute for Regenerative Medicine | Creasey O.A.,Center for Cellular and Molecular Engineering | And 9 more authors.
Stem Cells Translational Medicine | Year: 2014

Stem cells are promising candidate cells for regenerative applications because they possess high proliferative capacity and the potential to differentiate into other cell types. Mesenchymal stem cells (MSCs) are easily sourced but do not retain their proliferative and multilineage differentiative capabilities after prolonged ex vivo propagation. We investigated the use of hypoxia as a preconditioning agent and in differentiating cultures to enhance MSC function. Culture in 5% ambient O2 consistently enhanced clonogenic potential of primary MSCs from all donors tested. We determined that enhanced clonogenicity was attributable to increased proliferation, increased vascular endothelial growth factor secretion, and increased matrix turnover. Hypoxia did not impact the incidence of cell death. Application of hypoxia to osteogenic cultures resulted in enhanced total mineral deposition, although this effect was detected only in MSCs preconditioned in normoxic conditions. Osteogenesisassociated genes were upregulated in hypoxia, and alkaline phosphatase activity was enhanced. Adipogenic differentiation was inhibited by exposure to hypoxia during differentiation. Chondrogenesis in three-dimensional pellet cultures was inhibited by preconditioning with hypoxia. However, in cultures expanded under normoxia, hypoxia applied during subsequent pellet culture enhanced chondrogenesis. Whereas hypoxic preconditioning appears to be an excellent way to expand a highly clonogenic progenitor pool, our findings suggest that it may blunt the differentiation potential of MSCs, compromising their utility for regenerative tissue engineering. Exposure to hypoxia during differentiation (post-normoxic expansion), however, appears to result in a greater quantity of functional osteoblasts and chondrocytes and ultimately a larger quantity of high-quality differentiated tissue. © AlphaMed Press.

Lozito T.P.,Center for Cellular and Molecular Engineering | Alexander P.G.,Center for Cellular and Molecular Engineering | Lin H.,Center for Cellular and Molecular Engineering | Gottardi R.,Center for Cellular and Molecular Engineering | And 3 more authors.
Stem Cell Research and Therapy | Year: 2013

Osteoarthritis (OA), the most prevalent form of arthritis, affects up to 15% of the adult population and is principally characterized by degeneration of the articular cartilage component of the joint, often with accompanying subchondral bone lesions. Understanding the mechanisms underlying the pathogenesis of OA is important for the rational development of disease-modifying OA drugs. While most studies on OA have focused on the investigation of either the cartilage or the bone component of the articular joint, the osteochondral complex represents a more physiologically relevant target because the disease ultimately is a disorder of osteochondral integrity and function. In our current investigation, we are constructing an in vitro three-dimensional microsystem that models the structure and biology of the osteochondral complex of the articular joint. Osteogenic and chondrogenic tissue components are produced using adult human mesenchymal stem cells derived from bone marrow and adipose seeded within biomaterial scaffolds photostereolithographically fabricated with defined internal architecture. A three-dimensional-printed, perfusion-ready container platform with dimensions to fit into a 96-well culture plate format is designed to house and maintain the osteochondral microsystem that has the following features: an anatomic cartilage/bone biphasic structure with a functional interface; all tissue components derived from a single adult mesenchymal stem cell source to eliminate possible age/tissue-type incompatibility; individual compartments to constitute separate microenvironment for the synovial and osseous components; accessible individual compartments that may be controlled and regulated via the introduction of bioactive agents or candidate effector cells, and tissue/medium sampling and compositional assays; and compatibility with the application of mechanical load and perturbation. The consequences of mechanical injury, exposure to inflammatory cytokines, and compromised bone quality on degenerative changes in the cartilage component are examined in the osteochondral microsystem as a first step towards its eventual application as an improved and high-throughput in vitro model for prediction of efficacy, safety, bioavailability, and toxicology outcomes for candidate disease-modifying OA drugs. © 2013 BioMed Central Ltd.

PubMed | Center for Cellular and Molecular Engineering and University of Pittsburgh
Type: | Journal: Journal of tissue engineering and regenerative medicine | Year: 2017

Traumatized muscle, such as that debrided from blast injury sites, is considered a promising and convenient tissue source for multipotent progenitor cells (MPCs), a population of adult mesenchymal stem cell (MSC)-like cells. The present study aimed to assess the regenerative therapeutic potential of human traumatized muscle-derived MPCs, e.g., for injury repair in the blast-traumatized extremity, by comparing their pro-angiogenic potential in vitro and capillary recruitment activity in vivo to those of MSCs isolated from human bone marrow, a widely-used tissue source. MPCs were tested for their direct and indirect effects on human microvascular endothelial cells (ECs) in vitro. The findings reported here showed that MPC-conditioned culture medium (MPC-CM), like MSC-CM, promoted EC-cord network branching. Silent (si)RNA-mediated silencing of vascular endothelial growth factor-A (VEGF-A) expression in MPCs attenuated this effect. In a chick embryonic chorioallantoic membrane in vivo angiogenesis assay, MPCs encapsulated in photocrosslinked gelatin scaffold recruited blood vessels more efficiently than either MSCs or human foreskin fibroblasts. Together, these findings support the potential application of traumatized muscle-derived MPCs in cell-based regenerative medicine therapies as a result of their influence on EC organization. Copyright 2017 John Wiley & Sons, Ltd.

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