Cartilage shows lousy regenerative capabilities. Fortunately, it is possible to regenerate cartilage with human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) that have been embedded in a hyaluronic acid (HA) hydrogel composite. In fact, such a combination has shown remarkable results in rat and rabbit models.
In this present study, published in Stem Cells Translational Medicine, Yong-Geun Park and his colleagues from SungKyunKwan University School of Medicine, in Seoul, South Korea sought to confirm the efficacy of this protocol in a in a pig model using three different hUCB-MSC cell lines.
Park and his coworkers generated full-thickness cartilage injuries in the trochlear groove of each knee in 6 minipigs. Three weeks later, an even larger cartilage defect, 5 mm wide by 10 mm deep, was created, followed by an 8-mm-wide and 5-mm-deep boring. In short, the knee cartilages of these minipigs were very messed up.
To these knee cartilages, a mixture (1.5 ml) of hUCB-MSCs (0.5 × 107 cells per milliliter) and 4% HA hydrogel composite were troweled into was then cartilage defects of the right knee. The left knee served as an untreated control. Each cell line was used in two minipigs.
12 weeks after surgery, the pigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and more detailed microscopic analysis of the knee tissue. The transplanted knee showed superior and more complete joint-specific (hyaline) cartilage regeneration compared with the control knee. The microscopic characteristics of the knee cartilage showed that those animals that received the hUCB-MSCs had greater rates of cell proliferation and cells that differentiated into cartilage-making cells.
These data show consistent cartilage regeneration using composites of hUCB-MSCs and HA hydrogel in a large animal model. These experiments could be a stepping stone to a human clinical trial in the future that treats osteoarthritis of the knees with hUCB-MSCs embedded in HA hydrogel.