Allogenic Umbilical Cord Tissue for Rotator Cuff Injuries

Evaluation of the management of rotator cuff injuries utilising superparamagnetic iron oxide tracking stem cells

BACKGROUND

The ultrastructure of the tendon-bone interface (TBI) is inherently complex. After arthroscopic reconstruction, it is often replaced by disorganized scar tissue, which increases the risk of re-tearing.Stem cell therapies offer a promising approach to regenerate the original tissue structure and enhance the healing environment. The effectiveness of these therapies depends on understanding the localization, proliferation, and overall behavior of the implanted stem cells. This study aimed to track the distribution of stem cells in a rat model of rotator cuff injury using Magnetic Resonance Imaging (MRI) and superparamagnetic iron oxide nanoparticles (SPIO) and to evaluate the mechanisms and therapeutic effects of stem cell therapy.

METHODS

Adipose-derived mesenchymal stem cells (ADSCs) were isolated and expanded, then labeled with SPIO at an optimized concentration. The visibility of these labeled cells was assessed via MRI, along with evaluations of their viability, potential toxicity, and migration capacity in vitro.For the in vivo study, rats with rotator cuff tears were divided into two groups: a control group that received a PBS injection, and a treatment group that received SPIO-labeled ADSCs (designated as S-A). MRI scans were conducted at 1, 2, and 4 weeks post-surgery, followed by histological analysis after the rats were euthanized. At 8 weeks post-surgery, rats were sacrificed, and their shoulder joints were analyzed biomechanically and histologically to assess the overall treatment efficacy.

RESULTS

SPIO nanoparticles were successfully incorporated into ADSCs, and MRI imaging demonstrated that these SPIO-labeled cells significantly enhanced MRI contrast without affecting cell viability, proliferation, or migration ability. Both MRI and histological analyses confirmed that the implanted stem cells survived and remained localized for at least two weeks. Further histological and biomechanical evaluations indicated that the stem cells facilitated the repair of the TBI. This repair process appeared to be mediated by an increase in M2 macrophage activity within the injured tissue, promoting improved local healing conditions.

CONCLUSION

This study confirms that labeling ADSCs with SPIO nanoparticles is an effective method for tracking these cells in vivo using MRI, providing a non-invasive approach to monitor the repair of injured TBI. Moreover, the localized survival of transplanted stem cells supports their role in enhancing TBI repair by modulating the local inflammatory response.

Biologics in rotator cuff repair

Rotator cuff tears are common in middle-aged and elderly patients. Despite advances in the surgical repair of rotator cuff tears, the rates of recurrent tear remain high. This may be due to the complexity of the tendons of the rotator cuff, which contributes to an inherently hostile healing environment. During the past 20 years, there has been an increased interest in the use of biologics to complement the healing environment in the shoulder, in order to improve rotator cuff healing and reduce the rate of recurrent tears. The aim of this review is to provide a summary of the current evidence for the use of forms of biological augmentation when repairing rotator cuff tears.