Ultrasonographic and Histological Correlation after Experimental Reconstruction of a Volumetric Muscle Loss Injury with Adipose Tissue.

Fernando Leiva-Cepas,Jose Peña-Amaro,Fernando Jimenez-Diaz,Ignacio Ruz-Caracuel,Rafael Villalba,Maria Jesus Gil-Belmonte,Alberto Benito-Ysamat,Ignacio Jimena

doi:10.3390/ijms22136689

Abstract

Different types of scaffolds are used to reconstruct muscle volume loss injuries. In this experimental study, we correlated ultrasound observations with histological findings in a muscle volume loss injury reconstructed with autologous adipose tissue. The outcome is compared with decellularized and porous matrix implants. Autologous adipose tissue, decellularized matrix, and a porous collagen matrix were implanted in volumetric muscle loss (VML) injuries generated on the anterior tibial muscles of Wistar rats. Sixty days after implantation, ultrasound findings were compared with histological and histomorphometric analysis. The muscles with an autologous adipose tissue implant exhibited an ultrasound pattern that was quite similar to that of the regenerative control muscles. From a histological point of view, the defects had been occupied by newly formed muscle tissue with certain structural abnormalities that would explain the differences between the ultrasound patterns of the normal control muscles and the regenerated ones. While the decellularized muscle matrix implant resulted in fibrosis and an inflammatory response, the porous collagen matrix implant was replaced by regenerative muscle fibers with neurogenic atrophy and fibrosis. In both cases, the ultrasound images reflected echogenic, echotextural, and vascular changes compatible with the histological findings of failed muscle regeneration. The ultrasound analysis confirmed the histological findings observed in the VML injuries reconstructed by autologous adipose tissue implantation. Ultrasound can be a useful tool for evaluating the structure of muscles reconstructed through tissue engineering.

Highlights

Ultrasound is an extremely important tool in the assessment of both normal and pathological skeletal muscle structure
We experimentally proved that the implantation of autologous adipose tissue in a Volumetric muscle loss (VML) injury significantly favored muscle neoformation, albeit with structural abnormalities [24]
We correlated ultrasound observations with histological findings of the anterior tibial muscles of rats 60 days after implanting different scaffolds in a muscle defect caused by a VML injury

Summary

Introduction

Ultrasound is an extremely important tool in the assessment of both normal and pathological skeletal muscle structure. In conjunction with the regenerative capacity of the host muscle itself, these materials may or may not promote the formation of new muscle tissue [11,12,13] In this situation, it is important to achieve functional recovery, and to determine whether a structure like that of healthy muscle is generated. The integration of bioscaffolds or materials into skeletal muscle has been followed by ultrasound assessment in a human trial [14] and an equine model [15], with the ultrasound analyses primarily being used to locate the implants in both studies This tool has been used to conduct guided biopsies of scaffold implantation territories with a view to assess the characteristics of the newly formed muscle [16]

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