Treating Skeletal Muscle Injures with Pluristem’s PLacental eXpanded (PLX) Cells Print E-mail
By William R. Prather RPh, MD   
Monday, 28 March 2011 01:11
best penny biotech stock picksInjuries to muscle are common. It has been reported that skeletal muscles are involved in up to 55% of all injuries sustained in sports. Woods et. al. has estimated that hamstring tears (defined as “preventing player participation in a match”) account for approximately 11-16% of all soccer and football-related muscle injuries, with about six players per team sustaining a hamstring injury each season in those sports. Additionally, in a study conducted by Castro et. al., examination of shoulders in 122 autopsy specimens ranging from 58 to 95 years of age found 28.7% with partial, and 30.3% with full rotator cuff tears. All of the tears in the study involved the supraspinatus muscle and frequency increased with age.

In the United States, strains (tears) of the adductors, hip flexors, quadriceps, pectoral and hamstring muscles account for more than a million office visits to doctors every year. On the job, leg strains, sprains and tears are the second most common type of work-related injury in American adults, with approximately 100,000 cases reported annually to the U.S. Bureau of Labor Statistics.

Intentional Muscle Injury Market Segment

In contrast to the unintentional muscle injury market, the intentional muscle injury market comprises those patients who, post-operatively, have potential weaknesses to the skeletal muscles. For example, it has been estimated that an incisional hernia will develop in approximately 10-15% of abdominal incisions. With more than 4 million abdominal surgeries performed in the United States every year, this translates into approximately 500,000 incisional hernias annually in the U.S. alone.

Current Therapy

Recovery time for muscle injuries can range from a few days to several weeks depending on the muscle involved and the severity of the tear. For example, a mild grade I hamstring strain may allow you to continue exercising lightly with a recovery time usually short, 1-2 weeks. A second-degree strain may require rest from the activity with recovery time averaging 3-4 weeks. The most severe (third degree) strains may require surgery with a recovery time up to ten weeks if there is no recurrence of the strain. The mainstay of therapy for muscle injury is primarily RICE (rest, ice, compression, elevation). Corticosteroid injections into the afflicted muscle are currently the most common pharmacologic therapy while some physicians are using platelet rich plasma (PRP), primarily in sports injuries. PRP is an autologous therapy that requires processing the patient’s own blood. Well controlled clinical trials with PRP to document the efficacy of these treatments are pending.

There are however, other treatments that are currently undergoing testing that may significantly alter the way muscle injuries are treated.

Pluristem's Approach

One such treatment is being developed by Pluristem Therapeutics (NASDAQ: PSTI; TASE:PLTR), an Israel-based biotechnology company developing cell therapies derived from the human placenta. The company recently announced the results of a pre-clinical animal study demonstrating that the local administration of PLX cells following muscle injury resulted in significant improvement in the recovery of muscle function when compared with the control group. This study suggests that Pluristem's PLX cells have the potential to treat various types of accidental and intentionally induced muscle injuries.

Pluristem’s patented mesenchymal stromal cell-like product, PLX (PLacental eXpanded) cells, are a drug delivery platform that releases a mixture of therapeutic proteins in response to a host of local and systemic inflammatory diseases. PLX cells are grown using the Company’s proprietary 3D micro-environmental technology without inducement or manipulation of the cells in any way. The result is an “off-the-shelf” product that requires no tissue matching prior to administration.

While the Company's first indication is for the treatment of critical limb ischemia, the end stage of peripheral artery diseases (PAD), Pluristem is planning to sponsor a physician’s IND in the US for use of the PLX cells in muscular sports injuries, primarily hamstring tears, as well as planning to pursue a Phase II clinical trial testing the use of PLX cells to improve the rehabilitation of the pelvic girdle muscles after hip replacement.

Skeletal Muscle Injury Types

Skeletal muscle injury can be divided into (a) shearing injuries in which both the myofibers and the framework of the connective tissue are torn (e.g. sports injuries) and (b) injuries in situ, in which only the myofibers are damaged (e.g. cutting or incisional injuries). After skeletal muscle trauma the tissue reacts with initial inflammation, followed by a regeneration of myofibers and finally the development of fibrosis.

The initial inflammatory reaction in this sequence provides an ideal target for PLX cells as inflammatory, ischemic tissue communicates with administered PLX cells that, in turn, secrete a tailored cocktail of anti-inflammatory and pro-angiogenic proteins that results in the restoration of blood flow via angiogenesis and healing of the inflammation.

Worldwide Market

When examining the worldwide potential for their treatment, Pluristem believes the worldwide unintentional muscle injury market for PLX cells is approximately $6 billion annually when assuming the administration of PLX cells as part of the medical armamentarium of Grade II muscle strains and as adjunctive to surgical therapy in Grade III and higher tears. Additionally, Pluristem believes the worldwide market for use of PLX cells to repair incisional hernias is approximately $1 billion annually. In addition, Pluristem believes PLX cells can be used for other incisional indications, such as the rehabilitation of the pelvic girdle muscles after hip replacement.

About the Author:

William R. Prather RPh, MD is the Senior VP Corporate Development at Pluristem Therapeutics.

He is a Registered Pharmacist as well as a Board Certified Internist and Geriatrician. Dr. Prather received his BS in Pharmacy (1970) and medical degree (1973) from the University of Missouri. He practiced internal medicine in the Kansas City, MO and Vail, CO areas until leaving Internal Medicine in 1987 to pursue a Fellowship in Geriatric Medicine at Harvard University. He completed this Fellowship in 1989.

In 1992 Dr. Prather left the practice of medicine to pursue a career in the financial industry where he has held Senior Healthcare research positions for a variety of investment banks. Dr. Prather co-founded Panacos, Inc. (NASDAQ:PANC), a public pharmaceutical company. Additionally, he has been on the Boards of several public and private companies, including Boston Biomedica Inc. (a public medical diagnostics company), PriMed (a private medical device company), MdBio (a Maryland healthcare venture firm), and sat on the Advisory Board of MDS Capital Management, (a Canadian venture firm).

Dr. Prather submitted this article solely for the purpose of providing key expert analysis and opinion. No compensation was exchanged by either party in consideration for the publication of this material. If you are a science or medical expert willing to share your specific intelligence with our readers through your own Expert Briefing, please contact us.

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