Abstract
Advances in tissue engineering have enabled the ability to design and fabricate biomaterials at the nanoscale that can actively mimic the natural cellular environment of host tissue. Of all tissues, cartilage remains difficult to regenerate due to its avascular nature. Herein we have developed two new hybrid polypeptide-glycosaminoglycan microfibrous scaffold constructs and compared their abilities to stimulate cell adhesion, proliferation, sulfated proteoglycan synthesis and soluble collagen synthesis when seeded with chondrocytes. Both constructs were designed utilizing self-assembled Fmoc-protected valyl cetylamide nanofibrous templates. The peptide components of the constructs were varied. For Construct I a short segment of dentin sialophosphoprotein followed by Type I collagen were attached to the templates using the layer-by-layer approach. For Construct II, a short peptide segment derived from the integrin subunit of Type II collagen binding protein expressed by chondrocytes was attached to the templates followed by Type II collagen. To both constructs, we then attached the natural polymer N-acetyl glucosamine, chitosan. Subsequently, the glycosaminoglycan chondroitin sulfate was then attached as the final layer. The scaffolds were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), atomic force microscopy and scanning electron microscopy. In vitro culture studies were carried out in the presence of chondrocyte cells for both scaffolds and growth morphology was determined through optical microscopy and scanning electron microscopy taken at different magnifications at various days of culture. Cell proliferation studies indicated that while both constructs were biocompatible and supported the growth and adhesion of chondrocytes, Construct II stimulated cell adhesion at higher rates and resulted in the formation of three dimensional cell-scaffold matrices within 24 h. Proteoglycan synthesis, a hallmark of chondrocyte cell differentiation, was also higher for Construct II compared to Construct I. Soluble collagen synthesis was also found to be higher for Construct II. The results of the above studies suggest that scaffolds designed from Construct II be superior for potential applications in cartilage tissue regeneration. The peptide components of the constructs play an important role not only in the mechanical properties in developing the scaffolds but also control cell adhesion, collagen synthesis and proteoglycan synthesis capabilities.
Highlights
Recent advances in biomaterial synthesis coupled with improvements in tissue engineering (TE)techniques have resulted in the development of implantable materials for bone, bladder, skin and blood vessel regeneration [1]
Two separate fibrous scaffolds were prepared for potential applications in cartilage tissue regeneration
Both scaffolds were formed by utilizing Fmoc-valyl cetyl amide (FVC) fibers as templates which were bound to extracellular matrix (ECM)-mimicking components
Summary
Techniques have resulted in the development of implantable materials for bone, bladder, skin and blood vessel regeneration [1]. Such materials have shown promise as alternative means to repair damaged tissue through the utilization of biological or synthetic materials that stimulate cellular and tissue growth [2,3]. Cartilage is a specialized tissue which functions to enable stable and smooth movements of joint surfaces and allows for the dissipation of mechanical loads under physiological conditions [7]. Degradation of cartilage, articular cartilage on the surface of joints is correlated with age-related changes in chondrocyte function [8]. Focal chondral defects can be painful or disabling and may predispose patients for osteoarthritis [9,10]
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