[Show abstract][Hide abstract] ABSTRACT: Autologous fat transplantation is a common technique for soft tissue augmentation in aesthetic and reconstructive surgery; however, the degree of fat graft take can be unpredictable. Hyaluronan has been shown to be a promising cell carrier in adipose tissue engineering.
The authors investigate the effect of a hyaluronan hydrogel on fat graft survival, angiogenesis, and volume maintenance in a rat model.
Fat was harvested from the groins of 27 rats, processed, and injected beneath the animals' dorsums to form 2 grafts: 1 containing fat alone and 1 containing fat and hyaluronan hydrogel in a 1:1 mix (fat-HA). The grafts were scanned in vivo under high-resolution computed tomography at baseline and prior to euthanasia at 4, 12, and 20 weeks to measure total fat-HA graft volume as well as the volume of the fat component alone. Histological studies were performed after sacrifice to evaluate fat necrosis and blood vessel density.
All grafts were clinically viable. Overall, fat necrosis was significantly reduced in the fat-HA grafts compared with the grafts containing fat alone (P < .001). This difference was most profound at 4 weeks (P = .008) but did not reach statistical significance at 12 and 20 weeks. At 12 weeks, blood vessel density in the fat-HA grafts was significantly greater than in the grafts containing fat alone (P = .016), but this did not reach statistical significance at 4 or 20 weeks. At 20 weeks, the fat component of the fat-HA graft had significantly less volume loss than the fat-alone graft (P = .008).
When mixed with fat, hyaluronan hydrogel can improve early fat graft survival and may enhance vascularity and prolong volume maintenance.
No preview · Article · Jul 2012 · Aesthetic surgery journal / the American Society for Aesthetic Plastic surgery
[Show abstract][Hide abstract] ABSTRACT: Folliculogenesis within the ovary requires interaction between somatic cell components and the oocyte. Maintenance of 3-dimensional (3-D) architecture and granulosa-oocyte interaction may be critical for successful in vitro maturation of follicles. Testing of novel biomaterials for the 3-D culture of follicles may ultimately lead to a culture model that can support the longer in vitro culture intervals needed for in vitro maturation of human oocytes from ovarian tissue biopsies.
A novel tyramine-based hyaluronan (HA) hydrogel was tested for its biocompatibility with ovarian follicles. The HA was prepared at concentrations from 2 to 5 mg/ml. HA hydrogel was also formulated and tested with matrix proteins (ECM). Enzymatically isolated pre-antral follicles from the ovaries of 10-12 day SJL pups were divided amongst control (CT) and HA treatments. The growth of both fresh and vitrified follicles was assessed after encapsulation in the hydrogel. The basal culture medium was MEM alpha supplemented with FSH, LH, ITS and 5% FBS. Maturation was triggered by addition of hCG and EGF after in vitro culture (IVC). Outcome parameters monitored were follicle morphology, survival after IVC, antrum formation, GVBD and MII formation. Differences between treatments were analyzed.
HA and ECM-HA encapsulated follicles looked healthy and maintained their 3-D architecture during IVC. In control cultures, the follicles flattened and granulosa:oocyte connections appeared fragile. Estradiol secretion per follicle was significantly higher by Day 12 in ECM-HA compared to HA or CT (4119, 703 and 1080 pg/ml, respectively). HA and ECM-HA cultured follicles had similar survival rates (62% and 54%, respectively), percent GV breakdown (96-97%), MII formation (47-48%) and oocyte diameters at the end of IVC. Control cultures differed significantly in percent GVBD (85%) and MII formation (67%) . Vitrified-warmed follicles encapsulated in HA had an oocyte maturation rate to MII of 54% as compared to 57% in non-embedded follicles.
Initial testing of this new and unique HA-based hydrogel was quite promising. The ease of follicle encapsulation in HA, its optical transparency and ability to be molded combined with its support of follicle growth, estradiol secretion and resumption of meiosis make this HA-hydrogel particularly attractive as model for 3-D ovarian follicle culture.
[Show abstract][Hide abstract] ABSTRACT: Goals/Purpose: Autologous fat transplantation is a widely used technique for soft tissue augmentation in both aesthetic and reconstructive surgery. Volume maintenance is thought to be maximized by the injection of small amounts of fat in multiple areas thus enhancing rapid neovascularization. In spite of meticulous efforts, fat graft take can be unpredictable. Carriers and matrix design have been suggested to provide a favorable environment for cell growth and angiogenesis. Hyaluronan has been shown to be a promising cell carrier in adipose tissue engineering.
Methods/Technique: Fat was harvested from the groins of 27 rats, rinsed with lactated Ringer's solution, left to drain on Telfa and meticulously cut into very small injectable pieces. The processed fat was injected using 1 cc Luer-Lok syringes and a 16 gauge angiocatheter in multiple passes beneath the rat's dorsum forming two implants (0.8 cc each). The first implant contained fat alone and the second contained fat and hyaluronan (HA 4 mg/ml concentration) in 1:1 mix (Fat-HA). CT scan of the implants in vivo was performed at base line and at 4 weeks (n=8), 12 weeks (n=8) and 20 weeks (n=9). Scans were performed with a GE Locus high resolution small animal CT scanner using a soft tissue protocol. Fat and hyaluronan densities were determined by scanning a tube containing rat fat and another containing the hyaluronan material that had the same concentration used in this study. Volumetric analysis was performed of all implants. Fat-HA implants volume was measured as a whole. In addition, the fat component's volume was measured based on the difference in density between fat and hyaluronan. Rats were sacrificed in three groups at the same time intervals and histological studies were performed with hematoxylin and eosin and CD 31 stains. Wilcoxon signed rank tests were performed to evaluate changes within animal, and the Kruskal-Wallis test followed by the Steel-Dwass multiple comparison procedure was used to compare sacrifice times. A p-value of 0.05 was considered statistically significant.
Results/Complications: One rat died from anesthesia and another from the 12-week group was excluded from volumetric analysis due to incomplete image capture of the implants. All grafts in all animal groups were clinically viable. Fat volume change (as measured by CT scan analysis), measured as percentage change from baseline was significantly different (smaller) for both fat and Fat-HA measures, at all time intervals. However, at 20 weeks, the fat component of the Fat-HA implant had significantly less volume loss than the fat only implant (p=0.008). Overall, fat necrosis was significantly less in the Fat-HA measures as compared to the fat alone measures (p<0.001). This difference was most profound at 4 weeks (p=0.008). However, differences at 12 and at 20 weeks did not reach statistical significance. At 12 weeks, the blood density measures for the Fat-HA implants were significantly greater than fat alone (p=0.016). However, this did not reach statistical significance at 4 or at 20 weeks. No significant correlations were observed between blood vessel density and the development of fat necrosis in each implant.
Conclusion: Hyaluronan was compatible with adipose tissue and may act as a carrier to enhance cell viability, and angiogenesis. Although resorption was observed in both implants, the Fat-HA showed more fat volume maintenance at long term follow up. This technology may provide technical advancements in small volume fat grafting of contour defects in facial and breast reconstruction. Further research is needed using human adipose tissue and different hyaluronan concentrations.
Table 1: Differences in the changes in fat necrosis (%) by sacrifice time are shown. Medians and quartiles are provided.
Fat Necrosis (%)
60.00 (47.50, 63.75)
5.00 (0.00, 5.00)
5.00 (1.00, 10.00)
Fat-HA Necrosis (%)
5.00 (3.75, 13.75)
0.00 (0.00, 0.00)
0.00 (0.00, 1.00)
Difference Between Sides - Necrosis
-50.00 (-55.00, -43.75)
0.00 (-5.00, 0.00)
-5.00 (-9.00, -1.00)
* Fat only represents the fat component in the Fat-HA graft, i.e. (Fat-HA) HA.
Figure 1, Fat and hyaluronan in a Luer-Lok Tip syringe.
Figure 2, Fat and hyaluronan in a Luer-Lok Tip syringe after mixing.
Figure 3, Fat alone in a Luer-Lok Tip syringe after mixing.
Figure 4, Rat dorsum immediately after injection of fat alone and fat mixed with hyaluronan on either side of the midline.
Figure 5, Fat + hyaluronan graft after harvest at 4 weeks.
Figure 6, Fat + hyaluronan graft after harvest at 4 weeks with cross section. Notice clinical viability of fat well incorporated within hyaluronan gel.
Figure 7, Fat alone graft after harvest at 4 weeks.
Figure 8, CT scan image of fat + hyaluronan implant with 3 D reconstruction.
[Show abstract][Hide abstract] ABSTRACT: In vitro ovarian follicle culture is a new frontier in assisted reproductive technology with tremendous potential, especially for fertility preservation. Folliculogenesis within the ovary is a complex process requiring interaction between somatic cell components and the oocyte. Conventional two-dimensional culture on tissue culture substrata impedes spherical growth and preservation of the spatial arrangements between oocyte and surrounding granulosa cells. Granulosa cell attachment and migration can leave the oocyte naked and unable to complete the maturation process. Recognition of the importance of spatial arrangements between cells has spurred research in to three-dimensional culture system. Such systems may be vital when dealing with human primordial follicles that may require as long as three months in culture. In the present work we review pertinent aspects of in vitro follicle maturation, with an emphasis on tissue-engineering solutions for maintaining the follicular unit during the culture interval. We focus primarily on presenting the various 3-dimensional culture systems that have been applied for in vitro maturation of follicle:oocyte complexes. We also try to present an overview of outcomes with various biomaterials and animal models and also the limitations of the existing systems.
Full-text · Article · Oct 2010 · Reproductive Biology and Endocrinology