Soft Tissue to Bone Healing in Rotator Cuff Repair - Structural Interfaces and Attachments in Biology - page 261

human rotator cuff fibroblasts were cultured on the scaffold [ 79 ]. The fibroblasts
deposited a proteoglycan and collagen matrix onto the scaffold, which contained
both collagen types I and II. A fibrocartilage transition zone was also identified.
12.7.4 Stem Cells
There has been recent interest in the field of orthopaedic surgery in utilizing
mesenchymal stem cells to assist with regeneration. Studies have evaluated the
effect of stem cells specifically in the setting of rotator cuff repair using rodent
models. Application of bone marrow derived mesenchymal stem cells alone did not
improve rotator cuff healing based on biomechanical and histological evaluation
[ 80 ]. Similarly, bone marrow derived stem cells transfected with BMP 13 did not
effect healing [ 81 ]. There was no difference in the amount of new cartilage
formation, collagen fiber organization, or biomechanical properties. However,
when bone marrow derived stem cells were transduced with scleraxis (a transcrip-
tion factor necessary for tenogenesis), there was improvement in rotator cuff
healing. Its expression in osteoblastic cell lines may also induce chondrocyte-like
gene expression, which may be important at the bone-tendon junction. When stem
cells transfected with adenoviral-mediated scleraxis were applied to the rotator cuff
healing site in a rodent model, there were improvements in biomechanical and
histological properties [ 82 ]. These studies highlight the potential value of mesen-
chymal stem cells as a delivery mechanism for factors which may improve healing
of the rotator cuff.
12.7.5 Platelet Rich Plasma
PRP is a sample of autologous blood with high concentrations of platelets above
baseline values. Its application has been used for tendinopathy, muscle injury, and
tendon and ligament healing [ 83 , 84 ]. PRP use is compelling, as it contains
multiple growth factors, cytokines, and other proteins, all of which are active at
various phases of muscle or tendon healing. There are several commercially
available preparation systems, each one varying slightly from another. Generally,
the application of PRP works well in vitro [ 85 - 87 ]. Fibroblasts treated with PRP
have demonstrated increases in growth factors, MMP production, and collagen
production. Increases in cell proliferation and tendon regenerate material have
also been noted.
Unfortunately these benefits have not consistently translated to clinical
improvements. Randelli et al. demonstrated the safety of application of PRP in
the human setting [ 88 ]. Multiple other studies have not shown an improvement in
tendon healing with the use of PRP. Weber et al . presented a study showing no
differences in a randomized controlled study (Weber et al . , presented at the