الفهرس 
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Abstract
The survival of free fat used as an autograft is operator dependent and requires delicate handling of the graft tissue, careful washing of the fat to minimize extraneous blood cells, and installation into a site with adequate vascularity. There is evidence that fat cells will survive and that filling of defects is not from the residual collagen following cell destruction. There is some loss of fat after transplant, and most surgeons tend to overfill the recipient site.
As the rate of absorption of fat grafts is high, and can reach 70% by volume, satisfactory results with fat grafts are seen in the early post-transplantation period, while the long-term results of fat grafts are usually disappointing for both the surgeon and the patient. These unsatisfactory post-graft results frequently lead to the need for initial overcorrection and repeated surgery to preserve the volumes and contours of the recipient site. Unfortunately, initial overcorrection can induce serious problems, such as central necrosis of the fat grafts, which requires the surgical removal of the fat grafts in some cases. In addition, the repeated procedures after initial surgery increase the risk of fat absorption and graft failure, which are both associated with additional damage to the blood supply at the recipient site.
As it was also reported that the long-term viability of fat grafts depends on reanastomosis with the host vasculature, neovascularization of fat grafts and a non-infected recipient site, various methods to achieve the high viability of fat grafts without serious problems have been proposed. These include the concentration of harvested fat to increase the number of mature transplanted adipocytes, washing to eliminate inflammatory mediators and remove dead tissue, debris and blood and the use of liposuction with reduced negative pressure to decrease mechanical trauma to the harvested adipose tissue. However, many of these manipulations have failed to produce post-graft results that are fully satisfactory.The dissatisfaction with the viability of fat grafts has prompted many experimental and clinical attempts to increase their viability.
In this Current study, Fat tissue was degraded into its smallest unit, a single and separate fat cell with a large, single, lipid droplet and peripherally located nucleus, referred to as a unilocular fat cell (UFC). It is assumed that if the UFCs are grafted, the transplanted fat cells would spread into the tissues and result in greater cell survival.
This study was done at Ain Shams University Hospitals on 40 rats weighting 400 to 500 grams. Each rat was anesthetized by ketamine (40 mg/kg) and dormicum (40 mg/kg) intramuscularly and maintained as required. Fat tissue was harvested from the inguinal adipose tissue of the rat. After excising the autogenous fat grafts, the tissue was cut into pieces of approximately1-2 mm diameter. Fat was washed in saline and filtered using sterile lint-free paper. The harvest samples was drawn into a 5-cc syringe with an 18-gauge needle. Suction was standardized by placing the plunger at the 5-cc mark. Then it was divided into three groups:
Group A: Fat injected into the scalp in the form of large single parcel.
Group B: Fat injected into the scalp in the form of small parcels and thin strips
Group C: The adipose tissue from the excised fat was then be digested with a 0.02% collagenase solution in phosphate-buffered saline (PBS) at 37oC. The remaining tissue fragments was removed by filtering the digest through a 200-mm-pore filter. The digest will then be fractionated by centrifugation and the uni follicular cells was collected from the top layer using a syringe and injected into the scalp.
The fat from all groups was injected in the scalp of the same rat which was chosen as the recipient site for the fat graft, because of the absence of subcutaneous fat in this area, a fact that facilitates dissecting out the fat graft from this bounded site. Animals were cared according to the rules of the university committee. They were housed in a pathogen-free environment, given food and water, and exposed to a 12-h light-dark cycle. Also rats received proper analgesic and antibiotic
Post grafting assesment was done as follows:
Group A, B, C: before injecting the fat, it will be bottled in a syringe (whose weight is previously detected), and weighted over a sensitive scale, then at 90 days, Postgrafting tissue weights will be divided by pre implantation tissue weights to get the graft percent survival rates.
Group B: The viability of the adiposite will be assessed by Glucose Transport test, i.e. taking the adipose aspirates (5 ml) and transfer it to a plate with a 10-ml measuring pipette containing 10 ml of Dulbecco’s Modified Eagles’s Medium (DMEM) and 1 unit of regular insulin cultured at 37 oC with 5% CO2 for 1 h. The glucose concentration within DMEM solution will be measured by a biochemical analyzer. The fat cells will then be injected into the head skin of the rat.
At 90 days after implantation, all fat grafts will be harvested and fixed in 10% buffered formalin and embedded in paraffin and processed with H&E staining for histopathological examination.
Statistical analysis of the obtained data showed that after engraftment, the fat cells were able to effectively obtain a nutrient supply from the circulating plasma; therefore, the diameters of the injected UFCs recovered or enlarged. It showed overall survival rates 85.32 % with SD 5.35 when compared with the pearl technique that showed50.71 % with SD 6.28 and compared with bullous injection technique that showed mean survival rate of 38.37 % with SD
The grafted unilocular fat cells (UFCs) maintained a normal histologic structure post grafting. It showed higher survival rates when compared to the conventional methods without any of the evidence of necrosis, fibrosis, oil cysts, and vacuoles, which were seen histologically in conventional fat grafts.