External Volume Expansion in Irradiated Tissue: Effects on the Recipient Site.
External volume expansion prepares recipient sites to improve outcomes of fat grafting. For patients receiving radiotherapy after mastectomy, results with external volume expansion vary, and the relationship between radiotherapy and expansion remains unexplored. Thus, the authors developed a new translational model to investigate the effects in chronic skin fibrosis after radiation exposure.



Twenty-four SKH1-E mice received 50 Gy of β-radiation to each flank and were monitored until fibrosis developed (8 weeks). External volume expansion was then applied at -25 mmHg to one side for 6 hours for 5 days. The opposite side served as the control. Perfusion changes were assessed with hyperspectral imaging. Mice were euthanized at 5 (n = 12) and 15 days (n = 12) after the last expansion application. Tissue samples were analyzed with immunohistochemistry for CD31 and Ki67, Masson trichrome for skin thickness, and picrosirius red to analyze collagen composition.



All animals developed skin fibrosis 8 weeks after radiotherapy and became hypoperfused based on hyperspectral imaging. Expansion induced edema on treated sides after stimulation. Perfusion was decreased by 13 percent on the expansion side (p < 0.001) compared with the control side for 5 days after stimulation. Perfusion returned to control-side levels by day 15. Dermal vasculature increased 38 percent by day 15 (p < 0.01) in expansion versus control. No difference was found in collagen composition.



External volume expansion temporarily reduces perfusion, likely because of transient ischemia or edema. Together with mechanotransduction, these effects encourage a proangiogenic and proliferative environment in fibrotic tissue after radiotherapy in the authors' mouse model. Further studies are needed to assess these changes in fat graft retention.
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Michael S
MS
Chin
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Jorge
J
Lujan-Hernandez
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Oksana
O
Babchenko
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Elizabeth
E
Bannon
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Dylan J
DJ
Perry
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Ava G
AG
Chappell
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Yuan-Chyuan
YC
Lo
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Thomas J
TJ
Fitzgerald
Worcester, Mass.|From the Department of Radiation Oncology and the Division of Plastic Surgery, University of Massachusetts Medical School.
Janice F
JF
Lalikos
D000273:Adipose Tissue / Q000637:transplantation; D000818:Animals; D001610:Beta Particles / Q000009:adverse effects*; D003094:Collagen / Q000032:analysis; D004195:Disease Models, Animal; D004487:Edema / Q000209:etiology / Q000628:therapy; D005260:Female; D005355:Fibrosis; D006801:Humans; D016462:Mammaplasty; D051379:Mice; D008812:Mice, Hairless; D054843:Negative-Pressure Wound Therapy; D018919:Neovascularization, Physiologic; D010100:Oxygen / Q000097:blood; D011833:Radiation Injuries, Experimental / Q000628:therapy*; D011855:Radiodermatitis / Q000628:therapy*; D012867:Skin / Q000098:blood supply / Q000737:chemistry / Q000528:radiation effects; D012883:Skin Ulcer / Q000209:etiology / Q000628:therapy; D015626:Tissue Expansion / Q000379:methods; D015625:Tissue Expansion Devices
D003094:Collagen; D010100:Oxygen