title: Hyaluronan-based polymers in the treatment of osteochondral defects.
abstract: Articular cartilage in adults has limited ability for self-repair. Some methods devised to augment the natural healing response stimulate some regeneration, but the repair is often incomplete and lacks durability. Hyaluronan-based polymers were tested for their ability to enhance the natural healing response. It is hypothesized that hyaluronan-based polymers recreate an embryonic-like milieu where host progenitor cells can regenerate the damaged articular surface and underlying bone. Osteochondral defects were made on the femoral condyles of 4-month-old rabbits and were left empty or filled with hyaluronan-based polymers. The polymers tested were ACP sponge, made of crosslinked hyaluronan, and HYAFF-11 sponge, made of benzylated hyaluronan. The rabbits were killed 4 and 12 weeks after surgery, and the condyles were processed for histology. All 12-week defects were scored with a 29-point scale, and the scores were compared with a Kruskall-Wallis analysis of variance on ranks. Untreated defects filled with bone tissue up to or beyond the tidemark, and the noncalcified surface layer varied from fibrous to hyaline-like tissue. Four weeks after surgery, defects treated with ACP exhibited bone filling to the level of the tidemark and the surface layer was composed of hyaline-like cartilage well integrated with the adjacent cartilage. At 12 weeks, the specimens had bone beyond the tidemark that was covered with a thin layer of hyaline cartilage. Four weeks after surgery, defects treated with HYAFF-11 contained a rim of chondrogenic cells at the interface of the implant and the host tissue. In general, the 12-week defects exhibited good bone fill and the surface was mainly hyaline cartilage. Treated defects received significantly higher scores than untreated defects (p < 0.05), and ACP-treated defects scored significantly higher than HYAFF-11-treated defects (p < 0.05). The introduction of these hyaluronan-based polymers into defects provides an appropriate scaffolding and favorable microenvironment for the reparative process. Further work is required to fully assess the long-term outcome of defects treated with these polymers.
authors: Skeletal Research Center, Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106-7080, USA.
authors: L A
authors: LA
authors: Solchaga
authors: J U
authors: JU
authors: Yoo
authors: M
authors: M
authors: Lundberg
authors: J E
authors: JE
authors: Dennis
authors: B A
authors: BA
authors: Huibregtse
authors: V M
authors: VM
authors: Goldberg
authors: A I
authors: AI
authors: Caplan
mesh_terms: D000818:Animals; D018786:Bone Substitutes; D002358:Cartilage, Articular / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D020219:Chondrogenesis / Q000187:drug effects*; D005269:Femur / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D006820:Hyaluronic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use*; D007592:Joint Diseases / Q000188:drug therapy* / Q000601:surgery; D007719:Knee Joint / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D016348:Osseointegration; D011108:Polymers; D011817:Rabbits
chemical_list: D018786:Bone Substitutes; D011108:Polymers; C086358:hyaluronic acid benzyl ester; D006820:Hyaluronic Acid