Epidermal Growth Faktör (Egf) ve Egf Yüklenmiş Polikaprolakton Skafoldun Tendon Defekt İyileşmesine Etkileri
Koçyiğit, İsmail Aykut
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Introduction: In order to obtain the most accurate anatomical and histological tendon regeneration, therapies including the administration of platelet rich plasma (PRP), bone marrow aspiration, bone morphogenic protein, mesenchymal stem cells and growth factors ( bFGF, HGF, rhPDGF-BB, TGF-b, VEGF ) are being applied along with the conventional treatment. Epidermal growth factor (EGF) is a growth factor that stimulates cell growth, proliferation and differentiation through binding EGFR cell surface receptor. Its current clinical application includes the bridging in between epidermis fragments in skin regeneration. In this study, the aim was to investigate the potential role of EGF in tendon repair and regenaration which has not been investigated previously. Material and Methods: In this preclinical study, 1 cm size defects were created on one of the Achilles tendon of 30 New Zealand white rabbits. 3 experimental groups of 10 tendons were made including:(1) “Sham” group: 1 cm tendon defect was splinted leaving the gap with non absorbable suture; (2) EGF(+) group: 1 cm tendon defect was splinted leaving the gap with non absorbable suture and 25 µg/kg EGF injection was made in the defect; (3) Scaffold+ EGF(+) group: 1 cm tendon defect was grafted with biodegradable, porous polycaprolactone (PCL) scaffolds loaded with 25 µg/kg EGF and stabilized using non absorbable suture. In groups 2 and 3, same dose EGF injections were made every other day for 10 days. Animals were sacrificed at 8 weeks postop, and Achilles tendon repair and regeneration was investigated by histopathological and biomechanics analysis. The tissues were rapidly fixed in 10% formalin and processed for routine light microscopy. All specimens were embedded in paraffin, 10 mm sections were cut and stained by hematoxylin and eosin (H&E) and Masson’s trichrome. The biomechanical study was performed immediately after the animal was sacrificed and the tendons were maintained fresh. Pullout force test was performed for Achilles tendons and then was measured breaking force, amount of elongation at break and young modulus. All procedures were approved by Animal Research Ethical Committee.vii Results: It was observed macroscopically that defects healed and bridged in all of the experimental groups. Histologically, “Sham” group: Damar formation and Type 3 collagen have been observed to be newly constructed. Rare adiposity was observed EGF(+) group: vessel formation, peripheral nerve buds and more adipocytes were observed inside the tendon. A high level of type III collagen was detected which was laid by fibroblasts to be replaced by type I collagen eventually for complete tendon regeneration. Scaffold +EGF(+)group: vessel formation and peripheral nerve buds were again observed, but the amount of adipocytes and laid type III collagen were less compared to EGF(+) group. Type Ⅰ / Type Ⅲ collagen ratio was highest in Skafold + EGF group and at least in sham group. Biomechanically, there was no statistically significant difference between the 3 experimental groups and the control groups in terms of the breaking forces (p> 0,05). There was no significant difference between the groups in terms of the amount of elongation at break (p> 0,05). Young modulus was not significantly different between the three experimental groups (p> 0,05) but it was found that there was a significant difference between control group , EGF and Skafold + EGF groups (P <0,05). Conclusion: EGF application together with the conventional therapy led to more appropriate, advanced tendon regeneration histologically. Our hypothesis is; The histological demonstration that EGF application, increased vascularity, accumulation of "pericyte" cells (stem cells) adjacent to the endothelial cell in the vasculature, and appearance of the development of fat cells in the tendon defect region in order to provide the necessary energy for healing can provide high tissue repair. There was no significant difference between the groups in terms of breaking forces. EGF application did not negatively affect tendon healing in biomechanical aspects. It was observed that EGF without biomechanical adverse effects improves histologically more appropriate and advanced tendon healing by increasing the proportion of Type I / Type Ⅲ collagen. Histologically effective tendon healing was achieved by the addition of EGF. Treatment with EGF + scaffold was obtained the most effective tendon healing. Scaffold implantation into the defect as the void filler and by increasing the effectiveness of the growth factor, resulted in less type III collagen formation and thus faster tendon repair response.