A new area of medicine that has sparked interest in orthopedics is regenerative medicine. Great hopes are set on regenerative medicine to develop alternative therapies for cartilage damage, arthritis, large bone defects, and tendon ruptures. Stem cells are of particular interest in regenerative medicine. Stem cells are unspecialized cells, which have the ability to differentiate into different adult cell types. (1) Stem cells are self-renewing, clonogenic, multipotent in nature, and their main role is to maintain homeostasis by replacing damaged cells. (2) They can be activated to proliferate and differentiate into the required type of cell following the loss of cells or injury to the tissue. (2)
A patient’s own cells are used in stem cell therapy to limit potential rejection of the cells or negative immune responses. (1) More specifically, adult mesenchymal stem cells (MSCs) have the potential to differentiate into various mesenchymal lineages such as muscle, bone, cartilage, fat, tendon, and ligaments. (3) Regenerative medicine includes two different strategies of cell-based therapies. The first approach, “cell therapy”, involves using stem cells to replace previously damaged cells within a tissue to reconstitute its function. (1) During this procedure, cells in suspension are injected into the damaged tissue or blood circulation. (1) The second procedure, “tissue engineering”, is more complex. Stem cells are combined in a three dimensional matrix to compose a tissue-like construct to replace lost parts of the tissue, or even the whole organ. (1) Cell therapy is not able to regenerate large tissue defects or replace whole organs, so in those situations tissue engineering is the more promising strategy. (1) Tissue engineering is a relatively new area and more exploration is being done in this field. The potential impact of tissue engineering, however, will be groundbreaking. In the future, engineered tissues could reduce the need for organ replacement, and could greatly accelerate the development of new drugs that may cure patients, eliminating the need for organ transplants altogether. (4)
Tendon and ligament injuries are common, everyday problems in sports. Tendons and ligaments are specialized connective tissues that connect muscles to bone or two muscles together. (3) When injured, the main concern is that the impaired tissue will not be replaced by non-specialized scar tissue. (3) Scar tissue is fibrous tissue that forms when normal tissue is destroyed by a disease, injury, or surgery. (6) Without the formation of scar tissue after injury, the individual may experience soreness, pain with active and passive motion, and limited range of motion. (5) They may also have incomplete functional recovery. (6) Several possible avenues for this problem have been explored and MSCs have proven to be promising candidates. (3) Bone-marrow derived human adult stem cells have been shown to differentiate and integrate into ligament tissue. (3) This will help with athlete recovery and ensure that the individual is able to safely return to sport without detrimental consequences due to injury.
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