Preparation And Performance Of A Soft Tissue Augmentation Material Mainly Composed Of Calcium Alginate Microsphers(CAMs)

Soft tissue reconstruction is one of the main fields refer to both the reconstructive surgery and the aesthetic plastic surgery. Most soft tissue reconstructive cases need to augment or refill the soft tissue defects, namely, soft tissue augmentation. As a result, the demand for soft tissue augmentation materials has increased quickly. In this paper, calcium alginate microspheres(CAMs), which have been already widely used in cell immobilization and drug delivery systems, was employed and researched in the field of soft tissue augmentation.CAMs soft tissue augmentation agent was prepared by blending CAMs with alginate proportionally. The optimal proportion was 5:2 based on the preliminary experimental results of rheological behavior (plasticity) and injection property.An 8-week subcutaneous mouse model was used to determine its resorption in vivo. Construct geometry was optimally maintained, and 82 percent of the original volume was preserved at 8 weeks. The average diameter of the microspheres in the agent had some effect on the degree of the resorption. With the increase of the diameter, the resorption decreased. Meanwhile, chitosan modification of the microspheres had no significant effect on the resorption.The preliminary mechanism of the resorption was further discussed. It was thegel desegregation and its volume decrease under physiological conditions due to ion exchange between Ca2+ and non-gelling ions that resulted in the resorption in vivo. The gel of and out of the microspheres contributed the resorption together, but the microspheres in the agent played a key role in slowing down the resorption.The microspheres could be retrieved from the subcutaneous intactly at 8 weeks. Histollogically, the agent remained a uniform sheet surrounded by a thin fibrous capsule and a mild lymphocytic infiltrate was noted at the beginning and had resolved by 4 weeks. Furthermore, chitosan modification could improve the biocompatibility between the microspheres and the tissue surrounded them.The addition of mouse fibroblasts L929 seemed to enhance the ability of the agent to maintain the volume of the construct, and 97.6 percent of the original volume was preserved at 8 weeks. This might be due to that the presence of cells stiffened the gel, because no evidence for de novo formation of tissue from the cells that were introduced was found histologically. In addition, chitosan modification could improve the interactions between the microspheres and the cells to some extent.In conclusion, our results suggest that CAMs with the alginate gel could be a suitable agent for soft tissue augmentation.