Biological fixation of soft tissue-based grafts for anterior cruciate ligament (ACL) reconstruction poses a major clinical
challenge. The ACL integrates with subchondral bone through a fibrocartilage enthesis, which serves to minimize stress concentrations
and enables load transfer between two distinct tissue types. Functional integration thus requires the reestablishment of this
fibrocartilage interface on reconstructed ACL grafts. We designed and characterized a novel mechanoactive scaffold based on
a composite of poly-α-hydroxyester nanofibers and sintered microspheres; we then used the scaffold to test the hypothesis
that scaffold-induced compression of tendon grafts would result in matrix remodeling and the expression of fibrocartilage
interface-related markers. Histology coupled with confocal microscopy and biochemical assays were used to evaluate the effects
of scaffold-induced compression on tendon matrix collagen distribution, cellularity, proteoglycan content, and gene expression
over a 2-week period. Scaffold contraction resulted in over 15% compression of the patellar tendon graft and upregulated the
expression of fibrocartilage-related markers such as Type II collagen, aggrecan, and transforming growth factor-β3 (TGF-β3).
Additionally, proteoglycan content was higher in the compressed tendon group after 1 day. The data suggest the potential of
a mechanoactive scaffold to promote the formation of an anatomic fibrocartilage enthesis on tendon-based ACL reconstruction
grafts.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. This
study was funded by a research award from the Musculoskeletal Transplant Foundation.
Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.