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Pediatr Surg Int. 2018 Feb;34(2):129-135. doi: 10.1007/s00383-017-4179-z. Epub 2017 Nov 9.

Characterization of M1 and M2 polarization of macrophages in vascularized human dermo-epidermal skin substitutes in vivo.

Author information

1
Tissue Biology Research Unit, University Children's Hospital Zurich, August Forel Str. 7, 8008, Zurich, Switzerland. Agnes.Klar@kispi.uzh.ch.
2
Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland. Agnes.Klar@kispi.uzh.ch.
3
Tissue Biology Research Unit, University Children's Hospital Zurich, August Forel Str. 7, 8008, Zurich, Switzerland.
4
Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland.
5
Department of Plastic, Reconstructive, Esthetical and Hand Surgery, Kantonsspital Aarau, Aarau, Switzerland.
6
Department of Surgery, University Children's Hospital Zurich, Zurich, Switzerland.

Abstract

AIMS AND OBJECTIVES:

Vascularized bio-engineered human dermo-epidermal skin substitutes (vascDESS) hold promise for treating burn patients, including those with severe full-thickness wounds. We have previously shown that vascDESS promote wound healing by enhanced influx of macrophages and granulocytes. Immediately following transplantation, macrophages infiltrate the graft and differentiate into a pro-inflammatory (M1) or a pro-healing M2 phenotype. The aim of this study was to characterize the activation state of macrophages infiltrating skin transplants at distinct time points following transplantation.

METHODS:

Keratinocytes and the stromal vascular fraction (SVF) were derived from human skin or adipose tissue, respectively. Human SVF containing both endothelial and mesenchymal/stromal cells was used to generate vascularized dermal component in vitro, which was subsequently covered with human keratinocytes. Finally, vascDESS were transplanted on the back of immuno-incompetent rats, excised, and analyzed after 1 and 3 weeks using immunohistological techniques.

RESULTS:

A panel of markers of macrophage M1 (nitric oxide synthase: iNOS) and M2 (CD206) subclass was used. All skin grafts were infiltrated by both M1 and M2 rat macrophages between 1-3 weeks post-transplantation. CD68 (PG-M1) was used as a pan-macrophage marker. The number of CD68+CD206+ M2-polarized macrophages was higher in 3-week transplants as compared to early-stage transplants (1 week). In contrast, the number of CD68+iNOS+ M1 cells was markedly decreased in later stages in vivo.

CONCLUSIONS:

Macrophages exhibit a heterogeneous and temporally regulated polarization during skin wound healing. Our results suggest that the phenotype of macrophages changes during healing from a more pro-inflammatory (M1) profile in early stages after injury, to a less inflammatory, pro-healing (M2) phenotype in later phases in vivo.

KEYWORDS:

Adipose stem cells; Macrophages; Skin tissue engineering

PMID:
29124400
DOI:
10.1007/s00383-017-4179-z
[Indexed for MEDLINE]

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