Engineered tendon graft for rotator cuff repair
The present disclosure relates to tissue engineering, and more particularly to a method for treating or repairing rotator cuff or other tendon tears or damage using scaffold-free, 3-dimensional engineered tendon constructs.
1. A method of forming a tendon repair construct having a bone fixation end and a tendon-fixation end, comprising the steps of:
placing stem cells on a substrate in a fibrogenic growth medium without placing the stem cells in an exogenous scaffold;
forming a confluent tendon monolayer from the stem cells;
allowing for detachment of the confluent tendon monolayer from the substrate to form a three-dimensional scaffold-less tendon construct; and
placing two or more three-dimensional scaffold-less tendon constructs side by side lengthwise in culture in fibrogenic differentiation medium such that at a first end, the two or more three-dimensional scaffold-less tendon constructs fuse together to become the bone-fixation end of the tendon repair construct, and at a second end opposite the first end, the three-dimensional scaffold-less tendon constructs comprise unfused individual tendon prongs for the tendon-fixation end of the tendon repair construct.
2. The method of claim 1 , wherein the fibrogenic growth medium includes one or more of basic fibroblast growth factor, dexamethasone, ascorbic acid-2-phosphatase, and L-proline.
3. The method of claim 2 , wherein the fibrogenic growth medium includes both basic fibroblast growth factor and dexamethasone to proliferate formation of the confluent tendon monolayer.
4. The method of claim 1 , wherein the fibrogenic differentiation medium includes one or more of dexamethasone, ascorbic acid-2-phosphatase, L-proline, and transforming growth factor beta.
5. The method of claim 4 , comprising the step of increasing a rate of collagen production by including transforming growth factor beta in the fibrogenic differentiation medium.
6. The method of claim 5 , wherein the step of increasing the rate of collagen production occurs prior to full osteogenic differentiation.
7. The method of claim 1 , comprising the step of immunostaining the three-dimensional scaffold-less tendon construct for one or more markers, the one or more markers including collagen, fibronectin, and elastin.
8. The method of claim 1 , wherein the detachment of the confluent tendon monolayer is a spontaneous self-delamination.
9. The method of claim 8 , wherein the spontaneous self-delamination occurs after replacing the fibrogenic growth medium with dexamethasone.
10. The method of claim 1 , wherein the three-dimensional scaffold-less tendon construct has an extracellular matrix configured to control assembly of load-bearing collagen fibrils.
11. The method of claim 10 , wherein the load-bearing collagen fibrils are aligned in vivo.
12. The method of claim 11 , wherein the load-bearing collagen fibrils are aligned by glycosaminoglycans and proteoglycans in the extracellular matrix.
13. The method of claim 1 , further comprising the step of implanting the tendon repair construct into a torn or damaged site.
14. The method of claim 13 , further comprising the step of regenerating a native enthesis at an interface of bone and the tendon repair construct, wherein the native enthesis includes a fibrocartilage region having graded zones.
15. The method of claim 14 , wherein the graded zones include tendon, unmineralized fibrocartilage, mineralized fibrocartilage, and bone.