| arthritis (OA) is the most common form of arthritis. It is | | | | with prevention of cartilage breakdown or with |
| characterized by degeneration of the articular cartilage | | | | cartilage restoration has not been achieved. |
| (the gristle that caps the end of long bones in a joint) | | | | That is why MSCs have been attractive. MSCs are |
| and, ultimately, joint destruction. OA is a major cause | | | | cells that can be stimulated to differentiate along |
| of disability in older adults and the prevalence of the | | | | specific pathways, including cartilage production. In |
| condition is expected to increase over the next 20 | | | | contrast to existing cartilage tissue which needs to be |
| years with the graying of the population. In fact, it has | | | | surgically harvested from non-weight-bearing cartilage, |
| been estimated that more than 100, 000o Americans | | | | MSCs can be harvested from bone marrow. |
| cannot transfer from their bed to the bathroom as a | | | | Some evidence exists that tissue damage in |
| result of osteoarthritis of the hip or knee. | | | | osteoarthritis is due to depletion of MSC populations. |
| The burden of OA is made worse by the | | | | So why haven’t MSCs been used for OA |
| inadequacies of current therapies. | | | | treatment already? |
| Non drug and various drug treatments are used for | | | | First, questions exist as to whether MSCs obtained |
| early OA, but protection of articular cartilage has so | | | | from patient with OA differ functionally from those of |
| far not been available. Surgical intervention- meaning | | | | healthy people. |
| joint replacement- is often indicated when the | | | | Also, age-dependent decline in the differentiation |
| symptoms cannot be controlled and the disease | | | | capability of MSCs has been reported by some |
| progresses. | | | | investigators. |
| Because this is such a significant public health problem- | | | | However, it should be pointed out that when MSCs |
| ranking among the top ten diseases chronic diseases | | | | are harvested and concentrated properly, enough |
| impacting society- it has been an attractive target for | | | | MSCs with adequate differentiation potential can be |
| researchers as well as clinicians specializing in arthritis. | | | | isolated from patients with OA, irrespective of their |
| A potentially valuable tool has been multipotent adult | | | | age or the cause of their disease. These results |
| mesenchymal stem cells (MSCs), obtained from the | | | | indicate that MSCs for regeneration of cartilage in |
| bone marrow of normal adults. Many strategies have | | | | patients with OA is practical as well as feasible. |
| been studied and developed to possibly harness the | | | | How to deliver stem cells is the biggest question. Direct |
| ability of MSCs to differentiate into cartilage cells. | | | | into the joint injection of MSCs is, technically, the |
| Osteoarthritis is a complicated disease. Cartilage cells, | | | | simplest approach to OA therapy. Unfortunately, there |
| called chondrocytes, produce and secrete enzymes, | | | | is no guarantee and even less data to support the |
| such as matrix metalloproteinases and aggrecanases, | | | | effectiveness of this approach. |
| which corrode cartilage. | | | | Compared with direct into the joint injection, MSC |
| Interleukin 1 (IL-1) is an inflammatory chemical | | | | application to cartilage surfaces using a scaffold offers |
| messenger which makes these enzymes cause more | | | | more control. The scaffold may consist of either |
| damage. Stimulation of these factors leads to damage | | | | natural or synthetic material. (The scaffold technique is |
| to cartilage through both reduced synthesis as well as | | | | the one advocated and used at the Arthritis and |
| accelerated breakdown. Other inflammatory | | | | Osteoporosis Center of Maryland (301) 694-5800) |
| messengers such as tumor necrosis factor are also | | | | Another possible approach: MSCs can be introduced |
| involved in cartilage breakdown and, along with | | | | with various viral vectors. This permits delivery of |
| mechanical factors lead to worsening of the disease. | | | | genes that encode proteins that could potentially |
| Despite much research into development of inhibitors | | | | reverse some of the damage in OA. |
| of these molecules for use in treating OA, success | | | | |