This application relates to the preparation of grafts, implants, prostheses or other tissue constructs, typically for use as replacements for damaged or diseased bodily tissue. More particularly, this application relates to apparatus and methods for maturing or conditioning biopolymer tissue constructs prior to implantation of the construct in the body.
Tissue constructs are often used as grafts, implants or prostheses to replace diseased or damaged bodily tissue. Tissue needing replacement can include, for example, cartilage, tendon and ligament tissue. A fully functional replacement tissue should withstand at least the stresses and strains imposed by normal bodily activity on the type of tissue the construct is to replace. Furthermore, the construct should be biocompatible and integrable, in vivo, i.e., the construct should resemble a natural tissue so as to attract and interact with specific cells present in the body. The attracted cells further organize the construct and secrete specific biosynthetic products, such as extracellular matrix proteins and/or growth factors, that bind to the replacement construct, enabling it to degrade, remodel and regenerate as a fully functional replacement tissue. Such integration strengthens and conditions the construct to better perform as a replacement tissue.
Synthetic materials such as polyester fibers (Dacron.TM.) or polytetrafluorlethylene (PTFE) (Teflon.TM.) have been used extensively as replacements for bodily tissue, with some success. However, due to the poor biocompatibility of such synthetic materials, they often initiate persistent inflammatory reactions. Additionally, they do not readily breakdown and are not readily integrated with the body via remodeling by tissue cells.
It is also known to fabricate replacement constructs from structural biopolymer matrix components, such as collagen, that are extracted, purified and combined with specialized cells. The cells can organize, condense, and otherwise interact with the matrix proteins to create a tissue-like construct that can more closely resemble a natural tissue, and hence more readily integrate with the body than implants, grafts or prostheses based on synthetic materials. However, available biopolymer implants do not always have, or develop in vivo, the matrix complexity characteristic of the tissue they are to replace so as to become fully-functional replacements.
Therefore, there is a need for improved replacement tissue constructs that are stronger and more readily integrable with the bodily environment. Accordingly, one object of the invention is to provide methods and apparatus for producing improved replacement tissue constructs.
Another object of the invention is to provide replacement tissue constructs that are stronger and more capable of withstanding the stresses and strains imposed thereon by the rigors of bodily activity.
A further object of the invention is to provide apparatus for maturing and conditioning prostheses, grafts and implants to be more readily accepted by and integrable with the natural bodily environment.
Another object of the invention is to provide prostheses, grafts and implants that more readily resemble the tissues they are intended to replace.
Other general and more specific objects of the present invention will in part by obvious and will in part appear from the drawings and description which follow.