Bevacizumab Improves Achilles Tendon Repair in a Rat Model

Abstract

Background/Aims: Effective wound-healing generally requires efficient re-vascularization after injury, ensuring sufficient supply with oxygen, nutrients, and various cell populations. While this applies to most tissues, tendons are mostly avascular in nature and harbor relatively few cells, probably contributing to their poor regenerative capacity. Considering the minimal vascularization of healthy tendons, we hypothesize that controlling angiogenesis in early tendon healing is beneficial for repair tissue quality and function. Methods: To address this hypothesis, Bevacizumab, a monoclonal antibody blocking VEGF-A signaling, was locally injected into the defect area of a complete tenotomy in rat Achilles tendon. At 28 days postsurgery, the defect region was investigated using immunohistochemistry against vascular and lymphatic epitopes. Polarization microscopy and biomechanical testing was used to determine tendon integrity and gait analysis for functional testing in treated vs non-treated animals. Results: Angiogenesis was found to be significantly reduced in the Bevacizumab treated repair tissue, accompanied by significantly reduced cross sectional area, improved matrix organization, increased stiffness and Young's modulus, maximum load and stress. Further, we observed an improved gait pattern when compared to the vehicle injected control group. Conclusion: Based on the results of this study we propose that reducing angiogenesis after tendon injury can improve tendon repair, potentially representing a novel treatment-option.

Ultrasound Evaluation of Anti-Vascular Endothelial Growth Factor–Induced Changes in Vascular Response Following Tendon Injury

“…Histological measures of vascular density at day 7 support the reduction in vascular signal seen in the photoacoustic analyses. These results are supported by a recent study that also found reduced vascularity with the delivery of anti-VEGF at a similar dosage to our mid-dosage group (Tempfer et al 2018). The high-dosage group only caused a decrease in photoacoustic measures at day 7, with no changes in histological measures.…”

“…The anti-angiogenic drug, Bevacizumab, as well as the murine compatible version, B20.4-1-1, are direct inhibitors of vascular endothelial growth factor (VEGF) binding and have been shown in reduce vascularity in multiple disease models (Mancuso et al 2006;Okada et al 2010;Xiao et al 2016). New research has demonstrated that anti-angiogenic treatment in tendon models may cause improvements in tissue organization and mechanical properties (Dallaudiere et al 2013;Tempfer et al 2018). However, a thorough evaluation of how these treatments alter tendon vascularity in a dose-dependent manner has not been investigated.…”

Global Responses of Il-1β-Primed 3D Tendon Constructs to Treatment with Pulsed Electromagnetic Fields

“…Determination of apoptosis was performed by staining of cryosections with the In Situ Cell Death Detection Kit, Fluorescein (Roche, Vienna, Austria) according to the manufacturer´s recommendations. Quantification of TUNEL staining was performed using ImageJ software ImageJ software v. 150a [28]. Caspase3/7 activity was measured using protein lysates of tendon-like constructs and the Caspase-Glo ® 3/7 Assay (Promega, Vienna, Austria).…”

“…Polarization microscopy was used for the determination of the type I collagen fiber orientation and packing density. Birefringence intensity was measured by quantification of average pixel intensity using ImageJ software v. 150a [28]. For polarization microscopy, unstained sections of tendon-like constructs were imaged using a 10× or 16× objective equipped with a polarization filter mounted on an Axioplan microscope (Carl Zeiss, Jena, Germany).…”

Expression of TGF‑β1 and VEGF in patients with Achilles tendon rupture and the clinical efficacy

“…TGF-β1 and VEGF are important growth factors, as TGF-β1 promotes cell growth and development, wound healing, and modulation of immune responses (28), and VEGF is a powerful angiogenesis regulatory factor with an important influence on revascularization (29). A relevant study has shown that TGF-β1 and VEGF are highly expressed in an animal model of Achilles tendon injury (30), however, no clinical study has been carried out.…”