This open access review covers, in some detail, the state of development for stem cell therapies aimed at tendon regeneration. This is one of numerous tissues in the human body with normally limited regenerative capacity, and for which stem cell treatments offer the potential for complete healing. Progress towards that goal is, as ever, not as rapid as we'd like, however. Note that the full paper is PDF format only for the moment:
Tendon injuries are a common cause of physical disability. They present a clinical challenge to orthopedic surgeons because injured tendons respond poorly to current treatments without tissue regeneration and the time required for rehabilitation is long. New treatment options are required. Due to its relatively low cellularity and vascularity as well as the change in the tissue microenvironment after injury, tendons form scar tissue and ectopic bone after injury without regenerating the original tendon structure.
Tissue engineering with stem cells offers the potential to replace the injured/damaged tissues with healthy and functional ones. The use of stem cells for tendon tissue engineering is advantageous compared to terminally differentiated cells as stem cells are pluripotent or multipotent, highly proliferative and synthetic, and can provide the appropriate signals to promote tendon regeneration compared to terminally differentiated cells. Moreover, stem cells can also be used as a vehicle for gene therapy and sustained delivery of bioactive factors for tendon repair.
While the application of stem cells for the promotion of tendon healing is promising in small animal models, there have been few well-controlled large animal studies and clinical trials. The follow-up duration in animal studies was usually short (usually 4-12 weeks). Further research on the efficacy and safety of stem cell-based therapy for tendon repair in well-designed large animal models with extended follow-up time and randomized controlled clinical trials is needed.