Skeletal ligament healing using the recombinant human amelogenin protein

Abstract

Injuries to ligaments are common, painful and debilitating, causing joint instability and impaired protective proprioception sensation around the joint. Healing of torn ligaments usually fails to take place, and surgical replacement or reconstruction is required. Previously, we showed that in vivo application of the recombinant human amelogenin protein (rHAM +) resulted in enhanced healing of the tooth‐supporting tissues. The aim of this study was to evaluate whether amelogenin might also enhance repair of skeletal ligaments. The rat knee medial collateral ligament (MCL) was chosen to prove the concept. Full thickness tear was created and various concentrations of rHAM +, dissolved in propylene glycol alginate (PGA) carrier, were applied to the transected MCL. 12 weeks after transection, the mechanical properties, structure and composition of transected ligaments treated with 0.5 μg/μl rHAM + were similar to the normal un‐transected ligaments, and were much stronger, stiffer and organized than control ligaments, treated with PGA only. Furthermore, the proprioceptive free nerve endings, in the 0.5 μg/μl rHAM + treated group, were parallel to the collagen fibres similar to their arrangement in normal ligament, while in the control ligaments the free nerve endings were entrapped in the scar tissue at different directions, not parallel to the axis of the force. Four days after transection, treatment with 0.5 μg/μl rHAM + increased the amount of cells expressing mesenchymal stem cell markers at the injured site. In conclusion application of rHAM + dose dependently induced mechanical, structural and sensory healing of torn skeletal ligament. Initially the process involved recruitment and proliferation of cells expressing mesenchymal stem cell markers.

Regeneration of grade 3 ankle sprain, using the recombinant human amelogenin protein (rHAM+) in a rat model

“…Though complete and sharp transection of the CFL does not mimic the ankle sprain mechanism, this model offers isolated, accurate, and repeatable injury, which is not possible in other ankle sprain models 18 . The commonly used linear tensioning of the fibula and calcaneus, as was performed in our previous study of the MCL, 17 would not mimic the natural failure mechanism of the CFL in internal rotation. Furthermore, the structure of the rat calcaneus (similar to ball shape) made it practically impossible to firmly attach it to the Instron device.…”

“…Eight‐week‐old female Sabra rats (n = 56), mean weight of 250 g, were included in the study. On the basis of our previous results with transected MCLs, 17 we estimated the samples size of rats required to perform an experiment including four groups.…”

“…Previously, we showed that the application of the recombinant human amelogenin protein (rHAM + ), produced in our laboratory, 16 induces regeneration of the rat knee medial collateral ligament (MCL) 17 . Though clinically spontaneous healing (scarring) of knee MCL is sufficient in most patients, we chose this model because it is well established and involves a relatively long and superficial ligament.…”

Utilizing a Cortical Bone Trajectory Pedicle Screw for Lumbar Flexion-Distraction Injury

“…However, posterior ligamentous injury cannot be completely healed with PPS, so correction loss after removal of the instrument would be an issue of concern. Ligaments sometimes heal naturally, but unlike bone, the preinjury structure, organization, and biomechanical properties are not completely restored, because of the development of scar tissue [ 14 ].…”

Human gingival fibroblast response to enamel matrix derivative, porcine recombinant 21.3-kDa amelogenin and 5.3-kDa tyrosine-rich amelogenin peptide

“…It has also been detected in non-mineralizing tissues cells such as brain cells and haematopoetic cells. For this reason recombinant amelogenin is currently investigated as a potential healing or regeneration stimulator in reconstructive medicine [ 22 , 23 ]. However, until this moment non-specific amelogenin receptor was recognized [ 24 ], and only some receptors for different isoforms of amelogenin are suggested.…”