The effects of macrophage‐mediated inflammatory response to the donor site on long‐term retention of a fat graft in the recipient site in a mice model

Abstract

Inflammatory responses mediated by macrophages play a role in tissue repair. However, it is unclear whether the repair in the donor site after liposuction would have any effects on fat graft retention in the recipient site. This study is designed to evaluate the effects of a macrophage‐mediated inflammatory response in donor sites on long‐term retention of fat grafting. In this study, mice were randomly divided into two groups. One underwent simulated liposuction, called the fat procurement plus grafting (Pro‐Grafting) group, and the other underwent sham surgery, called the fat grafting only (Grafting Only) group. The prepared fat (0.3 ml each) was engrafted and cellular events over a 90‐day period were assessed. We found macrophages were infiltrated into adipose tissue at the recipient site in the Grafting Only group within 7 days and the repair essentially completed within 30 days. By contrast, few macrophages infiltrated the recipient site in the Pro‐Grafting group within 7 days and the entire remodeling process took 30 days longer in the Pro‐Grafting than the Grafting Only group. Moreover, C‐reactive protein levels were immediately upregulated after surgery, and the inflammatory factors' expression was higher at the donor rather than the recipient site. However, the repair processes and the long‐term retention rate became normal when the adipose tissue was grafted after the donor site did not require macrophages for repair. Therefore, we suggest higher inflammatory factors promote macrophage infiltration and the adipose tissue regeneration process at the donor site. This process is delayed at the recipient site, which may affect long‐term retention of fat grafts.

Hematopoietic stem cells can differentiate into pericytes and myofibroblast in wound healing, not bone Mesenchymal stem cells

“…It may be related to the different mice models used to construct the wound models. The recipient cells could migrate to the damaged site [30,31]. In our study, mice bone marrow is damage.…”

Recent Developments in Extracellular Matrix Remodeling for Fat Grafting

“…5.1 During the early stage after autologous fat grafting, circulating inflammatory cells, especially macrophages, will preferentially infiltrate the donor site. In this stage, the level of inflammation will be lower at the recipient than at the donor site, resulting in delayed repair of the recipient area, which may hinder the reconstruction of the ECM during the early stage ( Wang et al, 2020 ). Thus, early supplementation of the recipient area with an adequate number of macrophages may increase the graft retention rate by improving angiogenesis and ECM remodeling ( Phipps et al, 2015 ).…”

“…Excessive macrophage infiltration can also result in the excess secretion of type VI collagen and result in fibrosis ( Schnoor et al, 2008 ; Spencer et al, 2010 ). The rapid and massive infiltration and rapid evacuation of macrophages after fat grafting may lead to better tissue vascularization and facilitate ECM remodeling ( Anghelina et al, 2006 ; Wang et al, 2020 ). Therefore, trying to deplete the macrophages from transferred fat during the late stage may reduce the excessive deposition of ECM and reduce fibrosis ( Cai et al, 2017 ).…”

Effects of macrophage regulation on fat grafting survival: Improvement, mechanisms, and potential application—A review

“…By the way, Wang et al 24 proposed an interesting point: Due to the important role of macrophages in tissue regeneration, both the donor site and recipient site need to recruit macrophages after autologous fat grafting, but the number of macrophages in a certain time is limited, so would the repair of donor site have some impacts on fat survival in the recipient site? To verify the question, they designed a study and the results indicated that there was indeed a competition between the two sites.…”