2012 IR&D Annual Report

Novel Scaffolds for Tendon/Ligament Regeneration and Tissue Engineering Applications, SwRI-UTSA Connect Project, 18-R8253

Principal Investigators
Vasiliki Z. Poenitzsch
XingGuo Cheng
Rena Bizios (The University of Texas at San Antonio)

Inclusive Dates:  09/01/11 – 08/31/12

Background — This research is motivated by major clinical needs for tendon/ligament repair and by the current lack of innovative biomaterials for such applications. To date, material approaches in this field have not been successful because they lacked satisfactory biocompatibility, did not promote cell functions pertinent to new tissue formation and, most importantly, did not have the mechanical properties required for successful performance under the mechanical loading conditions that are characteristic to tendons and ligaments. This project investigated novel synthetic composite scaffolds containing aligned collagen and CNTs. Collagen is a naturally occurring, biocompatible and biodegradable material that is widely used as a tissue engineering and regenerative medicine matrix. CNTs are unique structures with remarkable mechanical properties. Combining of these two components has the potential to provide biomimetic, bioresorable, and mechanically competent composites for tendon/ligament repair.

Approach — The research was a multidisciplinary experimental study with two distinct, but complementary, components, one of which was accomplished at SwRI and the other at The University of Texas at San Antonio (UTSA). Specifically, SwRI personnel took the lead on fabrication and characterization of the novel constructs, and UTSA personnel concentrated on the in vitro assessment studies using cultured cell models. The overall objective of the research project was to design, fabricate, and establish the efficacy of novel scaffolds for tendon/ligament repair and regeneration. The two specific aims were to (1) fabricate unique collagen-CNT composite macrostructures with improved biochemical and biomechanical properties, and then (2) evaluate their efficacy for biomedical applications (such as tendon/ligament repair) by establishing their cytocompatibility in vitro using cultured adult mesenchymal stem cell (MSCs) models and investigating select cell functions pertinent to new tissue formation.

Images of collagen-CNT fibers
(a) A photograph of a collagen-CNT fiber. (b) Optical microscope image of collagen-CNT fiber and (c) collagen control (lacking CNTs) fiber. Scale bar is 1 cm for both images.

Accomplishments — SwRI has quantitatively demonstrated that aligned collagen-CNT fibers with improved mechanical properties can be fabricated. SwRI developed processes and procedures for the fabrication, and characterized the structure and mechanical performance of novel collagen-CNT based fibers. The collagen-CNT fibers have shown to contain a high loading and high degree of alignment of CNTs. Consequently, they have shown to be electrically conducting and to have 15 x increase in modulus and a 3 x improvement in strength as compared to aligned collagen fibers. Cellular experiments examining cytocompatibility as well as select MSC functions pertinent to new tendon/ligament formation are currently under way at UTSA. While this project focused on tendon/ligament repair, the real benefit of the project was establishing a capability for fabrication of aligned CNT-based wires that has application in the rapidly expanding field of nanotechnology.

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 10 technical divisions.