Decreased serum estrogen improves fat graft retention by enhancing early macrophage infiltration and inducing adipocyte hypertrophy.

BACKGROUND: Fat grafting is a commonly used procedure; however, the mechanisms that regulate graft outcomes are not clear. Estrogen has been associated with vascularization, inflammation and fat metabolism, yet its role in fat grafting is unclear. METHODS: Mice were implanted with 17ß-estradiol pellets (high estrogen, HE), underwent ovariectomy (low estrogen level, OVX) or sham surgery (normal estrogen level, CON). 45 days later, inguinal fat of mice was autografted subcutaneously. At 1, 2, 4, and 12 weeks post-transplantation, grafts were dissected, weighed, and assessed for histology, angiogenesis and inflammation level. RESULTS: Serum estrogen level correlated to estrogen manipulation. 12 weeks after autografting, the retention rate was significantly higher in the OVX (79% ± 30%) than in the HE (16% ± 8%) and CON (35% ± 13%) groups. OVX-grafts had the least necrosis and most hypertrophic fat. OVX recruited the most pro-inflammatory macrophages and demonstrated a faster dead tissue removal process, however a higher fibrogenic tendency was found in this group. HE grafts had the most Sca1+ local stem cells and CD31 + capillary content; however, with a low level of acute inflammation and insufficient adipokine PPAR-γ expression, their retention rate was impaired. CONCLUSIONS: Elevated serum estrogen increased stem cell density and early vascularization; however, by inhibiting the early inflammation, it resulted in delayed necrotic tissue removal and finally led to impaired adipose restoration. A low estrogen level induced favorable inflammation status and adipocyte hypertrophy to improve fat graft retention, but a continuing decreased estrogen level led to fat graft fibrosis.

Mechanical Micronization of Lipoaspirates for the Treatment of Horizontal Neck Lines.

BACKGROUND: Horizontal neck wrinkles develop as a result of the aging process. Stromal vascular fraction (SVF) gel, which is rich in extracellular matrix and functional cells, can be produced by a series of simple mechanical processes, including intersyringe shifting and centrifugation. This study aimed to assess stromal vascular fraction gel in the treatment of horizontal neck wrinkles. METHODS: This single-center study included female patients with horizontal neck wrinkles (Fitzpatrick types II to IV) treated with either SVF gel or botulinum toxin type A (BTX A) injection. SVF gel was first diffusely distributed subcutaneously along the neck line and then injected in a diluted way intracutaneously at points 0.5 cm apart along the horizontal lines. BTX A was injected at points 1.5 cm apart (2 U in each injection site). Satisfaction and improvement scores were compared between the two groups, and the collagen content of the neck wrinkle was compared by histologic evaluation before and after treatment. RESULTS: Twenty-eight patients received SVF gel and 22 received BTX A. In patients with type II neck wrinkles, BTX A and SVF gel treatment resulted in similar improvement scores and patient satisfaction in the first 3 months. In patients with type III and IV neck wrinkles, SVF gel resulted in significantly higher improvement scores and better patient satisfaction. A longer duration of adverse events was seen in the SVF gel treatment group. Histologic assessment suggested that SVF gel increased the collagen density of neck wrinkles. CONCLUSION: SVF gel is an effective treatment for horizontal neck wrinkles, particularly in patients with type III and IV wrinkles. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

3D co-culture model of endothelial colony-forming cells (ECFCs) reverses late passage adipose-derived stem cell senescence for wound healing.

BACKGROUND: Extensive passage of adipose-derived stem cells (ASCs) in vitro leads to loss of function. Endothelial colony-forming cells (ECFCs) can be isolated from adult peripheral blood. A 3D co-culture system may rescue in vitro ASC senescence. METHODS: A 3D co-culture model was successfully established using hyaluronic acid (HA) gel and a 10:1 ratio of late-passage ASCs and ECFCs. Cell density and culture conditions were optimized. Stem cell phenotype was characterized by flow cytometry. ELISA was used to measure the trophic effect of angiogenic growth factors and compare the effects of these factors between the 3-D co-culture and single-cell culture. Therapeutic potential of ASC/ECFC 3-D co-cultures was evaluated in a mouse chronic injury model. RESULTS: Following incubation in a HA substrate 3D co-culture system, ASC morphology, phenotype, secretory profile, and differentiation capacity were restored. The ASC/ECFC co-culture increased the secretion of cytokines, such as hepatocyte growth factor, compared with single-cell 3D culture or monolayer culture. Mice radiation-ulcer wounds treated with ASC/ECFC 3-D co-cultures (spheroids) showed epithelialization and improved healing compared with wounds treated with ASCs or ECFCs alone. Further, transplanted ASC/ECFC spheroids exhibited superior angiogenic potential due to the ability of the ASCs to transdifferentiate into pericytes. CONCLUSION: 3D co-culture of ECFCs and ASCs in vitro restored native ASC properties by reversing cellular senescence and loss of trophic function. Transplant of ASC/ECFC 3D spheroids in vivo demonstrated pro-angiogenic capacity with improved therapeutic potential.

Mechanical process prior to cryopreservation of lipoaspirates maintains extracellular matrix integrity and cell viability: evaluation of the retention and regenerative potential of cryopreserved fat-derived product after fat grafting.

BACKGROUND: Cryopreservation of fat grafts facilitates reinjection for later use. However, low temperature and thawing can disrupt tissues and cause lipid leakage, which raises safety concerns. Here, we compared the cryopreservation potential of stromal vascular fraction (SVF) gel processed from lipoaspirate with that of fat. METHODS: Human SVF gel and fat were cryopreserved at - 20 °C without cryoprotectant for 1 month. Fresh SVF gel and fat were used as controls. Tissue viability, adipose-derived stem cell (ASC) function, and the extracellular content were evaluated. At 3 months after transplanting the specimens to immunocompromised mice subcutaneously, the grafts were examined for retention, tissue engraftment, and inflammatory levels. The regenerative effect of cryopreserved SVF gel was evaluated in a murine ischemic wound healing model. RESULTS: At 1 month, the cell death rate in the SVF gel group was 36 ± 2%. The survived ASCs not only could be isolated via explant culture but also preserved colony-forming and differentiation. However, prolonged cryopreservation exacerbated apoptosis. Assessment of recovered tissues showed that the morphology, cell viability, and extracellular protein enrichment were better in SVF gel-preserved tissues than in frozen fat. At 3 months after lipotransfer, the retention ability of 1-month cryopreserved fat was 41.1 ± 9% compared to that of 1-month cryopreserved SVF gel. Immunostaining results showed that adipose tissue regeneration and integrity in the 1-month cryopreserved SVF gel group were superior to those of the cryopreserved fat group. The cryopreserved SVF gel also accelerated healing of the ischemic wound, compared with cryopreserved fat. CONCLUSION: Cryopreserved SVF gel maintained tissue integrity and cell viability and resulted in a better long-term retention rate than that of cryopreserved fat. Cryopreserved SVF gel also showed superior regenerative potential and improved ischemic wound healing.