TISSUE ENGINEERING SCAFFOLDS

Tissue Engineering Scaffolds

Tissue Engineering Scaffolds

Abstract

The design of new bioactive scaffolds mimicking the physiologic environment present during tissue formation is an important frontier in biomaterials research. Herein, we evaluated scaffolds prepared from blends of two biopolymers: silk fibroin and hyaluronan. Our rationale was that such blends would allow the combination of silk fibroin's superior mechanical properties with the biological characteristics of hyaluronan. We prepared scaffolds with porous microstructures by freeze-drying aqueous solutions of silk fibroin and hyaluronan and subsequent incubation in methanol to induce water insolubility of silk fibroin.

Introduction

An important objective in current tissue engineering research is the design of scaffolds that induce regenerative processes by interacting with relevant cell populations. To achieve this goal, a scaffold should act as a biomimetic platform allowing cells to properly accommodate and rebuild the target tissue. Scaffolds should feature physical and chemical cues that stimulate cell commitment, differentiation and regeneration of target tissues.(Rooney, (1993)

Silk fibroin (SF) and hyaluronan (HA) are two prominent biopolymers currently under study for the fabrication of tissue scaffolds. SF is a structural protein that can be extracted from silkworm silk. When appropriately purified, SF is non-toxic, non-immunogenic and has been demonstrated to support cell and tissue growth. Additionally, SF features outstanding mechanical properties that resemble those of several structural tissues in the body, and has been successfully explored for the tissue engineering of bone, cartilage and ligaments. In summary, SF is a well-established biomaterial for tissue scaffolding mainly owing to its amenability to form tissue conductive microstructures. On the other hand, no evidence has been found that Bombyx mori SF can interact with cell receptors, or actively trigger regenerative processes by itself.

Tissue culture

For tissue culture MSCs were suspended at a concentration of 106 cells per mL, and this suspension seeded onto prewetted scaffolds placed in 6-well non-tissue culture treated plates (Becton-Dickinson AG, Switzerland). Using this setup, cells were cultured for 2 h at 37 °C to allow cell attachment to the scaffolds. During this incubation step, 10 µl of DMEM were added to the scaffolds every 15 min to keep them wet. Afterwards, MSCs were cultured in DMEM with 10% fetal bovine serum, 0.1 mm non-essential amino acids, 50 µg/mL ascorbic acid-2-phosphate, penicillin G-streptomycin-amphotericin B, 10 nm dexamethasone and 1 ng/mL transforming growth factor-ß1 (TGF-ß1) for 21 days. The resulting tissues were evaluated biochemically, histologically, and for the expression of two marker genes.

Biochemical evaluation.( Chen, 2006)

For DNA analysis, ...