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1.  Fabrication and properties of acellular porcine anulus fibrosus for tissue engineering in spine surgery 
Over the last few years, new treatments for a damaged intervertebral disc (IVD) have included strategies to repair, replace, or regenerate the degenerative disc. However, these techniques are likely to have limited success, due to insufficiently effective means to address the damaged anulus fibrosus (AF). Here, we try to develop a bioprocess method for decellularization of the xenogeneic AF tissue, with a view to developing a scaffold as a potential candidate for clinical application in spinal surgery.
Porcine AFs were decellularized using freeze-thaw cycles, followed by various combined treatments with 0.1% sodium dodecyl sulfate (SDS) and nucleases.
Hematoxylin and eosin (H & E) staining showed that decellularization was achieved through the decellularization protocols. Biochemical analyses revealed 86% reduction in DNA, but only 15.9% reduction in glycosaminoglycan (GAG) content, with no significant difference in the hydroxyproline content. There was no appreciable cytotoxicity of the acellular AF. Biomechanical testing of the acellular AF found no significant decline in stiffness or Young’s modulus.
Porcine AF tissues were effectively decellularized with the preservation of biologic composition and mechanical properties. These results demonstrate that acellular AF scaffolds would be a potential candidate for clinical application in spinal surgery.
PMCID: PMC4264257  PMID: 25466788
Anulus fibrosus; Decellularization; Acellular; Disc degeneration; Intervertebral disc; Tissue engineering
2.  Hybrid Gel Composed of Native Heart Matrix and Collagen Induces Cardiac Differentiation of Human Embryonic Stem Cells without Supplemental Growth Factors 
Our goal was to assess the ability of native heart extracellular matrix (ECM) to direct cardiac differentiation of human embryonic stem cells (hESCs) in vitro. In order to probe the effects of cardiac matrix on hESC differentiation, a series of hydrogels was prepared from decellularized ECM from porcine hearts by mixing ECM and collagen type I at varying ratios. Maturation of cardiac function in embryoid bodies formed from hESCs was documented in terms of spontaneous contractile behavior and the mRNA and protein expression of cardiac markers. Hydrogel with high ECM content (75% ECM, 25% collagen, no supplemental soluble factors) increased the fraction of cells expressing cardiac marker troponin T, when compared with either hydrogel with low ECM content (25% ECM, 75% collagen, no supplemental soluble factors) or collagen hydrogel (100% collagen, with supplemental soluble factors). Furthermore, cardiac maturation was promoted in high-ECM content hydrogels, as evidenced by the striation patterns of cardiac troponin I and by upregulation of Cx43 gene. Consistently, high-ECM content hydrogels improved the contractile function of cardiac cells, as evidenced by increased numbers of contracting cells and increased contraction amplitudes. The ability of native ECM hydrogel to induce cardiac differentiation of hESCs without the addition of soluble factors makes it an attractive biomaterial system for basic studies of cardiac development and potentially for the delivery of therapeutic cells into the heart.
PMCID: PMC3196310  PMID: 21744185
Tissue engineering; Cardiac differentiation; Human embryonic stem cells; Biomaterial; Native cardiac matrix
3.  A Stimuli-Responsive Hydrogel for Doxorubicin Delivery 
Biomaterials  2010;31(31):8051-8062.
The goal of this study was to develop a polymeric carrier for delivery of anti-tumor drugs and sustained release of these agents in order to optimize anti-tumor activity while minimizing systemic effects. We used oligo(poly(ethylene glycol) fumarate) (OPF) hydrogels modified with small negatively charged molecules, sodium methacrylate (SMA), for delivery of doxorubicin (DOX). SMA at different concentrations was incorporated into the OPF hydrogel with a photo-crosslinking method. The resulting hydrogels exhibited sensitivity to the pH and ionic strength of the surrounding environment. Our results revealed that DOX was bound to the negatively charged hydrogel through electrostatic interaction and was released in a timely fashion with an ion exchange mechanism. Release kinetics of DOX was directly correlated to the concentration of SMA in the hydrogel formulations. Anti-tumor activity of the released DOX was assessed using a human osteosarcoma cell line. Our data revealed that DOX released from the modified, charged hydrogels remained biologically active and had the capability to kill cancer cells. In contrast, control groups of unmodified OPF hydrogels with or without DOX did not exhibit any cytotoxicity. This study demonstrates the feasibility of using SMA-modified OPF hydrogels as a potential carrier for chemotherapeutic drugs for cancer treatments.
PMCID: PMC2936247  PMID: 20696470

Results 1-3 (3)