In Vitro Tendon Engineering with Avian Tenocytes and Polyglycolic Acids: A Preliminary Report

Abstract

Although there are many reports of in vivo tendon engineering using different animal models, only a few studies involve the short-term investigation of in vitro tendon engineering. Our previous study demonstrated that functional tendon tissue could be engineered in vivo in a hen model using tenocytes and polyglycolic acid (PGA) fibers. This current study explored the feasibility of in vitro tendon engineering using the same type of cells and scaffold material. Tenocytes were extracted from the tendons of a hen's foot with enzyme digestion and cultured in DMEM plus 10% FBS. Unwoven PGA fibers were arranged into a cord-like construct and fixed on a U-shape spring, and tenocytes were then seeded on PGA fibers to generate a cell-PGA construct. In experimental group 1, 22 cell-scaffold constructs were fixed on the spring with no tension and collected at weeks 4 (n = 7), 6 (n = 7) and 10 (n = 8); in experimental group 2, five cell-scaffold constructs were fixed on the spring with a constant strain and collected after 6 weeks of culture. In the control group, three cell-free scaffolds were fixed on the spring without tension. The collected engineered tendons were subjected to gross and histological examinations and biomechanical analysis. The results showed that tendon tissue could be generated during in vitro culture. In addition, the tissue structure and mechanical property became more mature and stronger with the increase of culture time. Furthermore, application of constant strain could enhance tissue maturation and improve mechanical property of the in vitro engineered tendon (1.302 +/- 0.404 Mpa with tension vs 0.406 +/- 0.030 Mpa without tension at 6 weeks). Nevertheless, tendon engineered with constant strain appeared much thinner in its diameter than tendon engineered without mechanical loading. Additionally, its collagen fibers were highly compacted when compared to natural tendon structure, suggesting that constant strain may not be the optimal means of mechanical load. Thus, application of dynamic mechanical load with a bioreactor to the construction of tendon tissue will be our next goal in this series of in vitro tendon engineering study.

The past, present and future in scaffold-based tendon treatments

“…Although tendon-like tissues have been generated in vitro using TCs grown on PLGA electro-spun fibres, the de novo formed tissue was found to be significantly thinner and weaker than a natural tendon control [413]. However, mechanical stimulation of human foetal extensor tendon TCs loaded on electro-spun PLGA fibres promoted collagen alignment, produced a more mature collagen structure and created a stronger de novo tissue [414], suggesting that mechanical stimulation might be an optimal in vitro niche for engineering functional tendon equivalents ex vivo.…”

“…Porcine dermal fibroblasts and TCs loaded on PLGA electro-spun fibres have been shown to promote tenogenic function in vitro and improved healing, as evidenced by improved gross morphology, histological analysis and biomechanical properties, in vivo [413][414][415][416]. In conjugation with BMSCs, electro-spun PLGA scaffolds have demonstrated suppression of lymphocytes in vitro and improved biomechanical properties and acceptable integration into the native tendon tissue [417].…”

Design and Performance of an Optically Accessible, Low-Volume, Mechanobioreactor for Long-Term Study of Living Constructs

“…This has led tissue engineers to include mechanical stimulation in their construct formation protocols. [23][24][25][26][27][28][29][30][31][32][33] However, there is little data that elucidates how mechanical forces change the dynamics of fibroblast populations in cell culture systems. This is because most investigations are performed by examining the culture at fixed time points either during or after the mechanical stimulation protocol is complete.…”

Development of Novel Biodegradable Polymer Scaffolds for Vascular Tissue Engineering

“…Nonwoven PGA meshes have been used extensively by our group 15,16 and others to culture engineered vessels and other tissues such as cartilage, 18 skin, 19 tendon, and ligaments. 20,21 However, PGA-based tissues often contain polymer fragments at the end of culture. 15,16,22,23 To achieve a goal of creating biological connective tissues with minimal to no synthetic polymeric fragments in the final product, and hence maximal mechanical properties, there was an obvious need for a scaffold that degrades very rapidly, and yet supports cellular adhesion and collagenous matrix deposition.…”