Synergy of tendon stem cells and platelet-rich plasma in tendon healing.
Chen L, Dong SW, Liu JP, Tao X, Tang KL, Xu JZ. J Orthop Res. 2011 Dec 12. doi: 10.1002/jor.22033. [Epub ahead of print]
Tendon injuries occur frequently among both recreational and competitive athletes. The Achilles tendon and rotator cuff tears are by far the most common especially in athletes over the age of 30. Advances in tissue engineering and biologic growth factors have helped in developing ways to improve tendon healing. The use of platelet rich plasma (PRP) and stem cells have recently become popular and SMR has written several posts on this topic (see related posts below). However, the combined use of tendon stem cells and PRP has not been studied for its effect on tendon healing. Therefore, the purpose of this study was to examine the combined effect of PRP and tendon stem cells on Achilles tendon healing in both a loaded and unloaded condition in a rat model. Chen et al. used 96 rats which were divided into two groups (loaded and unloaded) and both groups were divided into 4 additional treatment subgroups (tendon stem cells, PRP, PRP and tendon stem cells, saline control). The unloaded groups were injected with botulinum toxin to inhibit muscle activity. All rats underwent a surgical Achilles tendon transection (near the attachment) without repair. The rats were then allowed normal activity until they were evaluated at 3 or 14 days following surgery. The tendons were examined for both protein and gene expression of several tendon healing markers (collagen I, collagen III, Tenascin C, and Smad8). The authors found that loaded tendons treated with control saline had higher collagen I gene expression and protein content at 3 and 14 days post injury compared to the unloaded tendons. Loaded tendons treated with just PRP had higher collagen I gene expression and protein content at 3 days post injury compared to unloaded tendons (gene expression was increased at 14 days post injury but the protein content was not). When examining the loaded tendons, the combination of PRP and tendon stem cells was the only intervention that had higher collagen I gene expression than the saline controls with loading.
Previous research has demonstrated that the loading tendons improve tendon healing by increasing the production of several growth factors and proteins that are required for tendon’s mechanical strength. Loading also helps to align collagen in the direction of loading which further improves tendon strength. The results of this study agree with these previous findings that loading improves tendon healing regardless of the treatment. This is demonstrated by the enhanced expression of collagen I in the loaded control saline group compared to the unloaded. The benefits of loading give further support for a previous post describing a new acronym (POLICE) which incorporates optimal loading with PRICE. Based off the results of this study, the optimal environment for tendon healing is a combination of tendon loading, PRP, and tendon stem cells. Clinically this may be a viable option in the future to augment tendon repair. By using the patient’s own biologic factors we can potentially get athletes back on the field faster and with less reoccurring injuries. Much more research is required to determine the effects in humans and the optimal combination of biologic factors and tendon loading. However, this study provides us with additional evidence to support the use of PRP and other biologic factors to improve healing. Has anyone seen patients receive other biologic factors to improve tendon healing besides PRP? Do you think this will ever significantly speed recovery time?
Written by: Stephen Thomas
Reviewed by: Jeffrey Driban
Chen L, Dong SW, Liu JP, Tao X, Tang KL, & Xu JZ (2011). Synergy of tendon stem cells and platelet-rich plasma in tendon healing. Journal of Orthopaedic Research PMID: 22161871