Role of xenogenous bovine platelet gel embedded within collagen implant on tendon healing: an in vitro and in vivo study

Abstract

Surgical reconstruction of large Achilles tendon defects is demanding. Platelet concentrates may be useful to favor healing in such conditions. The characteristics of bovine platelet-gel embedded within a collagen-implant were determined in vitro, and its healing efficacy was examined in a large Achilles tendon defect in rabbits. Two cm of the left Achilles tendon of 60 rabbits were excised, and the animals were randomly assigned to control (no implant), collagen-implant, or bovine-platelet-gel-collagen-implant groups. The tendon edges were maintained aligned using a Kessler suture. No implant was inserted in the control group. In the two other groups, a collagen-implant or bovine-platelet-gel-collagen-implant was inserted in the defect. The bioelectricity and serum platelet-derived growth factor levels were measured weekly and at 60 days post injury, respectively. After euthanasia at 60 days post injury, the tendons were tested at macroscopic, microscopic, and ultrastructural levels, and their dry matter and biomechanical performances were also assessed. Another 60 rabbits were assigned to receive no implant, a collagen-implant, or a bovine-platelet-gel-collagen-implant, euthanized at 10, 20, 30, and 40 days post injury, and their tendons were evaluated grossly and histologically to determine host-graft interactions. Compared to the control and collagen-implant, treatment with bovine-platelet-gel-collagen-implant improved tissue bioelectricity and serum platelet-derived growth factor levels, and increased cell proliferation, differentiation, and maturation. It also increased number, diameter, and density of the collagen fibrils, alignment and maturation of the collagen fibrils and fibers, biomechanical properties and dry matter content of the injured tendons at 60 days post injury. The bovine-platelet-gel-collagen-implant also increased biodegradability, biocompatibility, and tissue incorporation behavior of the implant compared to the collagen-implant alone. This treatment also decreased tendon adhesion, muscle fibrosis, and atrophy, and improved the physical activity of the animals. The bovine-platelet-gel-collagen-implant was effective in neotenon formation in vivo, which may be valuable in the clinical setting.

Role of Simvastatin on fracture healing and osteoporosis: a systematic review onin vivoinvestigations

“…42,49,88 Platelet rich plasma (PRP) and its other forms (gel and glue) can be obtained from patients' anticoagulant peripheral blood by one or two step centrifugation. 107,119,[121][122][123] PRPs are different from each other based on their platelet concentration which is 1.5 to 10 times greater than the physiologic plasma. In addition, they are different based on their source (auto-, allo-, and xenograft), and also presence/absence and concentration of white blood cells.…”

“…The most important growth factor of platelet concentrates is PDGF which is responsible for several osteoinductive and osteoconductive events. 4,119,121 Therefore, combination of PRP or PDGF with Simvastatin is an interesting option in inducing osteogenesis.…”

Application of Collagen Implants in Achilles Tendon Injuries

“…Collagen is a favorite material for tendon regeneration since it is the major ECM component in tendons. Several studies have demonstrated the applicability of different forms of collagen in tendon healing [25][26][27][28]. Collagen has well-documented structural, physical, chemical and immunological properties including high availability, easy purification from living organisms, low antigenicity, non-or low-cytotoxicity, good hemostatic and cell-binding properties as well as biological plasticity [10,29].…”

“…Two main issues with collagen include the low strength provided by collagen and its high degradation that is not desired for an ideal delivery system or carrier [34]. To overcome these issues and having a sustained release of growth factors, some researchers have fabricated the delivery systems to express lower degradation rate so that the scaffold can retain the growth factors for a long time at the implantation site [27,28,34]. Some researchers have cross-linked the collagen fibers with other biomaterials to enhance their biomechanical properties [35,36].…”

“…However, the growth factors such as BMPs are very expensive that limits their exogenous application on tendon healing [39]. Therefore, some researchers successfully embedded the platelet-rich plasma as a costeffective source of several growth factors within the tissue-engineered collagen-based implants to promote the healing and regeneration of large Achilles tendon defects in rabbits [25,26,28].…”