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The Effect of Pressure and Shear on Autologous Fat Grafting

Cheng, Chen M.D.; Xie, Yun M.D.; Li, Qingfeng M.D., Ph.D.

Author Information
Plastic and Reconstructive Surgery: March 2014 - Volume 133 - Issue 3 - p 419e-420e
doi: 10.1097/01.prs.0000438445.32659.59
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Sir

There have been many studies regarding the role of suction pressure in fat graft survival, but it remains an argumentative question mainly because there is no objective evaluation for the survival rate of a graft. In Lee et al.’s May 2013 study, “The Effect of Pressure and Shear on Autologous Fat Grafting,” it was found that pressure and shear are the two main, important variables determining fat graft survival.1 Higher aspiration pressures up to −0.83 atm did not affect fat graft viability in vivo. We congratulate Lee’s team on their efforts to systematically study the impact of these physical processing variables on fat harvest; however, we have some concerns about the evaluation methods used to study fat graft survival.

First, the conclusion of Lee et al.’s study was based mostly on gross histology and histology scoring; however, the effects of the staining procedure on the lipid droplets within the fat were neglected. Their histological study included fixation, paraffin embedding, tissue sectioning, and staining with hematoxylin and eosin. After these procedures, the triglycerides in lipid droplets would dissolve in lipophilic solvent and the fat tissue would display large, round vacuoles in cytoplasm. Therefore, it was not objective to evaluate whether there existed ruptured lipid droplets nor the survival rate of adipocytes using histology.

Second, Coleman’s research disagrees with Lee et al.’s study, implying that syringe suction was thought to minimize suction pressures during harvest.2 In our experience, even with syringe suction, impertinent pressure would affect fat graft outcomes. Higher pressure would cause more adipocyte rupture and more triglyceride overflow, which results in more lipid on the top layer (Fig. 1). On the other hand, the fat was harvested without any triglycerides, and the histological evaluation was also made on it. Since the section and staining procedure would dissolve the lipid within the adipocytes, even if there were large amounts of lipid rupture, it might not be found by the section and staining procedure. Therefore, it was not appropriate to base a conclusion on the regular histology or histology scoring.

Fig. 1
Fig. 1:
Different syringe suction samples with different outcomes. Low suction pressure would not do damage to fat (above, left), but high pressure would cause rupture of lipid droplets within adipocytes and show a layer of triglycerides above the fat layer (above, right). The difference between low (below, left) and high (below, right) pressure is more obvious after centrifugation.

Last but not least, besides morphology and histology, it was suggested that a glucose transport test might be an objective method to evaluate fat graft outcomes.3 As one kind of tissue with physiological function, we should evaluate both the histology and metabolic activity when studying graft viability. From our point of view, there still needs to be well-designed research on this basic, simple, and important problem: Will suction pressure ultimately impact graft outcomes?

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this communication.

Chen Cheng, M.D.

Yun Xie, M.D.

Qingfeng Li, M.D., Ph.D.

Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital

Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China

REFERENCES

1. Lee JH, Kirkham JC, McCormack MC, Nicholls AM, Randolph MA, Austen WG Jr.. The effect of pressure and shear on autologous fat grafting. Plast Reconstr Surg. 2013;131:1125–1136
2. Coleman SR. Structural fat grafting: More than a permanent filler. Plast Reconstr Surg. 2006;118(3 Suppl):108S–120S
3. Xie Y, Zheng D, Li Q, Chen Y, Lei H, Pu LL. The effect of centrifugation on viability of fat grafts: An evaluation with the glucose transport test. J Plast Reconstr Aesthet Surg. 2010;63:482–487

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