Chondroitin‐6‐sulfate incorporation and mechanical stimulation increase MSC‐collagen sponge construct stiffness

Abstract

Using functional tissue engineering principles, our laboratory has produced tendon repair tissue which matches the normal patellar tendon force-displacement curve up to 32% of failure. This repair tissue will need to withstand more strenuous activities, which can reach or even exceed 40% of failure force. To improve the linear stiffness of our tissue engineered constructs (TECs) and tissue engineered repairs, our lab is incorporating the glycosaminoglycan chondroitin-6-sulfate (C6S) into a type I collagen scaffold. In this study, we examined the effect of C6S incorporation and mechanical stimulation cycle number on linear stiffness and mRNA expression (collagen types I and III, decorin and fibronectin) for mesenchymal stem cell (MSC)- collagen sponge TECs. The TECs were fabricated by inoculating MSCs at a density of 0.14x106 cells/construct onto pre-cut scaffolds. Primarily type I collagen scaffold materials, with or without C6S, were cultured using mechanical stimulation with three different cycle numbers (0, 100, or 3000 cycles/day). After two weeks in culture, TECs were evaluated for linear stiffness and mRNA expression. C6S incorporation and cycle number each played an important role in gene expression, but only the interaction of C6S incorporation and cycle number produced a benefit for TEC linear stiffness.

Leveraging “Raw Materials” as Building Blocks and Bioactive Signals in Regenerative Medicine

“…36 However, raw material strategies using collagen type II to mimic the native ECM have been employed by other groups with similar success. 22,53,61 Contrasting data were obtained in a study by Ng et al, 32 where no difference was found between the effects of collagen type I and type II gels on mesenchymal stem cell proliferation and contraction. It is important to note, however, that differences in cell type, seeding density, seeding technique, and crosslinking method could all contribute to the discrepancy between these studies.…”

“…While most researchers tend to utilize raw materials that are present in the native ECM, cartilage tissue engineering solutions tend to conflict between the selection of type I and type II collagen (Table 3). Several raw material approaches utilize collagen type I to regenerate articular cartilage, 26,28,31,33,37,45,53,56,78 despite the well-known fact that the collagen of hyaline cartilage is predominately type II rather than type I. Studies by Berendsen et al 36 and Ng et al 32 attempted to address this raw material debate.…”

“…65,66 CS functions as a structural component of native ECM and strategies have utilized CS in tissueengineered constructs often with additional raw materials, such as HA and collagen, respectively. 53,67 The main motivation for blending CS with additional raw materials or synthetic polymers lies in its innate capability to be readily water soluble. 9 Some of the approaches used to overcome weaknesses and incorporate these raw materials will be discussed in the following sections.…”

“…In addition to the aforementioned CG scaffolds, CS has been blended with many synthetic polymers and raw materials. A study by Kinneberg et al 53 employed CS within a collagen hydrogel to investigate a potential increase in the linear stiffness of the gel constructs by helping to link discontinuous collagen fibrils in the gel network. Nguyen et al 96 designed a threelayer hydrogel scaffold with varying compositions of CS, HA, and polyethylene glycol (PEG) to simulate the mechanical properties of each zone of articular cartilage.…”

Bioreactor Design for Tendon/Ligament Engineering

“…Given these disadvantages, more researchers have turned their focus on exploring natural biomaterials. [19][20][21]37,[51][52][53][54] Being the main component of native tendon, collagen type I is the most obvious choice of material. Although the biocompatibility is excellent, the poor mechanical properties of reconstituted type I collagen scaffolds has limited their further development as a load-bearing material.…”