The influence of each step of the harvesting and grafting techniques on the viability of grafted fat. This study examines the influence of the intensity of the aspiration vacuum on the quality and viability of harvested adipose tissue. First we examine the pressures generated by different sizes of syringes and pulling back on the plunger at different levels. Then we investigate whether the level of vacuum used during suctioning affects the quality and viability of harvested fat.
Methods/Technique:
First, we developed a system to measure the vacuum generated by pulling back on the plunger of 10cc, 20cc and 60cc syringes at varying levels. The tip of the cannula was obstructed and an apparatus was designed to measure the force required to move the plunger to a given degree. In this model, the force is produced by a suspended mass subjected to gravity.
The chosen parameters for measurement were: pulling back the plunger to the 2cc or 5cc level of a 10cc syringe, to the 10cc level of a 20cc syringe, and to the 50cc level of a 60cc syringe. The intensity of the vacuum inside the syringe increases with pulling back on the plunger.
Next, human adipose tissue was harvested using a 15cm cannula with a 2.42mm internal diameter connected to a 10cc, 20cc 0r 60cc syringe with suction at various levels as noted in the above described parameters. All specimens were then refined by centrifugation at 1200g for 3 minutes, followed by decanting the oil, removing the aqueous level and wicking off any remaining oil. A 1cc aliquot of refined human fat obtained using each parameter was then infiltrated under the dorsal skin of four athymic nude Swiss mice using a 17 gauge blunt cannula.
4 months after transplantation, MRI at 11.75 Tesla was performed on the mice for volumetric analysis of the grafted fat. The grafted adipose tissue was then excised en bloc and examined for histology, collagen, and vessels.
The non-parametric test by Mann-Whitney was used for all statistical analysis, with the exception of the adipocyte surface analysis, in which the non-parametric test by Kolmogorov-Smirnov test was used. The threshold of significance (p) was set at 0.05.
Results/Complications:
Studies on the vacuum levels generated during suctioning revealed the following: pulling on a 10cc syringe to a level of 2cc (A) created a pressure of -0.37atm. Pulling to 5cc on a 10cc syringe (B) created -0.74 atm, 10cc on a 20cc syringe (C) created -0.76 atm, and to 50cc on a 60cc syringe (D) produced -0.81atm.
The volumetric MRI analysis showed no significant difference between groups A and B, but significant differences between A and the other groups (C and D). Histologic analysis demonstrated both a qualitative and a quantitative difference in level of degradation of grafted tissue depending on the intensity of vacuum suction used to aspirate it. Vascular staining revealed a regular decrease in stained vessels from group B progressing to non-vascularized fields in group D.
Collagen distribution was organized in group A but became progressively disrupted in groups B, C and D. The level of disruption was directly associated with the level of vacuum used in harvesting. A predominance of Collagen III in C and D reflects an inflammatory response.
Conclusion:
This study shows that the intensity of the vacuum is correlated with the pulling back on the plunger of the syringe. Furthermore, the induced vacuum does not depend on the type of syringe used, but on the volume of air expanded by the pulling back. Pulling back more than 5cc on a 10cc syringe in this study resulted in a significant decrease in the quality and viability of grafted fat. This study demonstrates that the intensity of the aspiration vacuum negatively influences the quality and viability of harvested adipose tissue.