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Nanomedical Biological Device in Development for Torn ACL Replacement. Francine Goulet , Ph.D., pht. INTRODUCTION.
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NanomedicalBiologicalDevice in Development for Torn ACL Replacement. Francine Goulet, Ph.D., pht
Ligaments, including ACL, extend between adjacent bone structures and serve a primary function of providing appropriate stability to the joints, especially when subjected to loads in tension or upon torsional movement. Type I collagen can be regenerated after tissue injury. However, the anterior cruciate ligament (ACL) has little ability to heal itself.
ACL REPLACEMENT 100, 000 total ruptures / yr (USA) 50,000 reconstructive surgeries / yr (USA)
Therapeutic options • Synthetic prostheses • Carbone • dacron • LAD • Allograft • Autograft
Option usedoften 1/3 patellar tendon + patella and tibia fragments
Clinical drawbacks • Knee joint fibrosis • Patellar impegement • Anterior knee pain • Patellar fracture • Patellar tendon’s rupture • Quads weaknesses
ACL : complex features • Ultrastructure: • Fibrocartilage • Sharpey’s fibers • Vascular network • Nervous receptors • Histological content: • Fibroblasts • Collagen fibers • Proteoglycans • Elastin…..
ACL: Knee stabilizer • Average length: 32 mm • Average diameter: 11 mm • Diam. at its insertions: 23 mm (femoral) and 30 mm (tibial) • Functional limits: • -Max. elongation: 6% (about 2 mm) • -Max. load: 1730 N (390 pds) • -Walking: 169 N • -Intensive sport: 400-500N
« LIGAMENTISATION » POST-IMPLANTATION 6 weeks; Vascularisation of the implant 30 weeks: histological and functional recoveries Questions: Innervation:? Mechanisms?
ACL tissue engineering Tissue engineering seems to be a promising alternative to produce ACL/ligament models: - for fundamentalstudies in vitro; - to develop tissue-emgineeredhuman ACL substitutes
ACL tissue engineering To understand ACL healing and to establish new options for torn ACL replacement, the potential of tissue-engineered collagen scaffolds has to be assessed in vitro and in vivo.
Tissue-engineered ACL Appropriate scaffold is needed to provide support and promote cell adhesion, migration and growth, leading to tissue regeneration. The scaffold must be biocompatible, biodegradable, suitable for cell attachment, and have a three-dimensional, porous structure. Since collagen is a major structural element in so many tissues and organs, collagen fibers are a logical choice for scaffolds.
Objective: Develop a new alternative for torn ACL replacement through the tissue-engineering approach. Hypothesis: Based on our expertise with tissue-engineeredhumanepidermal substitutes, wepostulatedthat ACL regenerationcanbeachieved by providing a biocompatible scaffoldthatcanbecolonized, remodeled and renewed by living cells in situ post-grafting.
We tested our collagen-based ACL scaffolds in the goat model…
ACL collagenscaffoldculturedwithout tension © F.G./LOEX
ACL collagenscaffoldsubjected to tension © F.G./LOEX
Collagenfibersalignment Before grafting Native ACL Periodicity: 67 nm © F.G./LOEX
Average cross section of 100 mm2 © F.G./LOEX