Tissue-engineered implants require appropriate biomaterials to serve the required physical function of the tissue being repaired or replaced while facilitating remodeling of the implant. We report on the development of implantable fabrics manufactured from continuous collagen threads. The collagen threads are formed by extrusion of native, acid-extracted bovine collagen into a buffered solution of polyethylene glycol, followed by rinsing and air drying. The high manufacturing rate of such threads permits the production of collagen fabrics of various configurations. The fiber diameter can be controlled, and threads with dry diameters as low as 25 microm have been produced. Braids and bundles of collagen threads implanted as a replacement of the anterior cruciate ligament in a dog model were completely remodeled into host tissue by 12 weeks. Knitted collagen fabrics implanted in a rat abdominal repair model prevented herniation, and connective tissue ingrowth was observed within the fabric by 12 weeks.

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Tissue engineering aims to develop clinical prostheses that are ultimately replaced by a functional, cell-produced matrix. For this goal to be achieved, the material must not only perform all the critical functions of the lost tissue immediately upon implantation, but also be replaced with new tissue at such a rate that tissue integrity is maintained. In the present study, prostheses formed from reconstituted collagen fibers were crosslinked to various levels with a carbodiimide; the same implant material was shown to be perceived in a variety of ways by its host. Variously crosslinked constructs were implanted in rats. Lightly crosslinked collagen fabrics implanted in abdominal wall defects remodeled into a fascia-like material within 90 days, in contrast to heavily crosslinked fabrics that were still persistent at this time point with little new tissue ingrowth and a marked foreign body reaction. However, the remodeling response was found to be site dependent, as heavily crosslinked collagen scaffolds implanted as anterior cruciate ligament (ACL) replacements in a dog model were adequately replaced by functional neoligamentous structures within 12 weeks.