Stem Cells in Orthopedics: A Comprehensive Guide for the General Orthopedist
The use of biologic adjuvants in the treatment of operative and nonoperative orthopedic injuries continues to expand in concert with our understanding of the acute and chronic healing process of musculoskeletal injuries. Stem cell treatments in orthopedics are among the most commonly explored options, and have found varying levels of success in promoting osseous and soft tissue healing. Basic science and translational studies have demonstrated the potential for broad application of stem cells in the treatment of a growing number of musculoskeletal injuries. Emerging clinical studies have also provided promising results, although the vast majority of studies have featured small sample sizes and limited duration of follow-up. In addition, a number of important questions remain regarding the clinical safety, treatment delivery, and overall efficacy of stem cell augmentation of injured tissue in orthopedics. The objective of the current review is to present a broad overview of the current state of stem cell treatments in orthopedic surgery, with an emphasis on soft tissue healing. This review of stem cell treatment covers the basic science behind biologic augmentation, advantages of the various stem cell sources, preclinical results, and current and future clinical applications.
The use of autologous MSCs in ACL healing remains limited to preclinical research and small case series of patients. One human trial by Silva and colleagues83 evaluated the graft-to-bone site of healing in ACL reconstruction for 20 patients who received an intraoperative infiltration of their graft with adult bm-MSCs. MRI and histologic analysis showed no difference in comparison to control groups, but the authors’ conclusion proposed that the number of stem cells injected might have been too minimal to show a clinical effect.
Other Applications
Although outside the scope of this article, stem cells have demonstrated efficacy in the treatment of a number of osseous clinical entities. This includes the treatment of fracture nonunion, augmentation of spinal fusion, and assistance in the treatment of osteonecrosis.84
Summary
As a scientific community, our understanding of the use of stem cells, their nuances, and their indications has expanded dramatically over the last several years. Stem cell treatment has particularly infiltrated the world of operative and nonoperative sports medicine, given in part the active patient population seeking greater levels of improvement.85 Stem cell therapy offers a potentially effective therapy for a multitude of pathologies because of these cells’ anti-inflammatory, immunoregulatory, angiogenic, and paracrine effects.86 It thus remains a very dynamic option in the study of musculoskeletal tissue regeneration. While the potential exists for stem cell use in daily surgery practices, it is still premature to predict whether this can be expected.
The ideal stem cell sources (including allogeneic or autologous), preparation, cell number, timing, and means of application continue to be evaluated, as well as those advantageous pathologies that can benefit from the technology. In order to better answer these pertinent questions, we need to make sure we have a safe, economic, and ethically acceptable means for stem cell translational research efforts. More high-level studies with standardized protocols need to be performed. It is necessary to improve national and international collaboration in research, as well as collaboration with governing bodies, to attempt to further scientific advancement in this field of research.49 Further study on embryonic stem cell use may be valuable as well, pending governmental approval. Finally, more dedicated research efforts must be placed on the utility of adjuncts with stem cell use, including PRP and scaffolds, which may increase protection, nutritional support, and mechanical stimulation of the administered stem cells.
