Mesoblast Ltd (MELBOURNE, Australia), a regenerative medicine company developing treatments for orthopaedic conditions, including the commercialization of a unique adult stem cell technology aimed at the regeneration and repair of bone and cartilage, announced successful preclinical trial results, which showed that its proprietary adult stem cells regenerated and regrew damaged knee cartilage. A single injection of stem cells was administered into postmenopausal ewes with well established knee osteoarthritis (OA). Three months after initial joint damage, the therapy resulted in sustained, progressive regeneration and regrowth of knee cartilage for at least 6 months.

In 18 postmenopausal ewes, OA developed following bilateral removal of the knee meniscus cartilage. Three months later, one group of six was examined to document the extent of OA prior to treatment, and the other two groups received hyaluronic acid alone in one knee and hyaluronic acid plus stem cells in the other knee. One of group was then followed for 3 months and another for 6 months. Six months after a single injection, OA knees that received the cells had as much as 20% to 25% thicker and greater area of cartilage lining the damaged joint than knees that received an injection of hyaluronic acid alone (both parameters P <.05). The cartilage was rich in proteoglycan suggesting that the regenerative process had induced normal, functional knee cartilage. In contrast, no significant improvement over baseline was seen with a single injection of hyaluronic acid at either 3 or 6 months.

Based on these cartilage regenerative results, Mesoblast will expand commercial product focus to include both postmenopausal and posttraumatic knee OA markets. The company has sufficient funds in place to initiate a phase II clinical trial of its allogenic stem cells in patients with OA of the knee, and will be actively seeking strategic partners with whom to commercialize its product for the broader OA markets, including postmenopausal women.

Mesoblast has the worldwide exclusive rights for a series of patents and technologies that have been developed over more than 10 years and which relate to the identification, extraction, and culture of adult Mesenchymal Precursor Cells (MPCs). The company has also acquired a substantial interest in Angioblast Systems Inc, a US company developing the platform MPC technology for the treatment of cardiovascular diseases.

Mesoblast recently announced, in conjunction with The Royal Melbourne Hospital, the successful use of its autologous adult stem cell technology in a clinical trial in which nonhealing bones were repaired. Ten patients with a total of 11 nonhealing fractures of the long bones in the legs were operated on using the company's proprietary stem cells. After completing 12 months of follow-up, eight achieved complete bony union poststem cell implantation, and another patient (with fractures of both the femur and tibia) achieved bony union of the tibia only, within a median time of 4 months. These same patients had a nonunited fracture for up to 41 months prior to cell implantation, with a median of 10 months. Of the eight patients who had successful long bone union, all have been able to fully bear weight on the treated leg and resume daily activities. No adverse events related to the stem cell therapy were reported. The remaining two patients had complex road trauma fractures involving multiple bones. Mesoblast intends to focus on a phase II Investigational New Drug submission to the US FDA for its allogeneic stem cells in the treatment of nonunion and high-risk fresh fractures.