Our results suggest that CAL is both effective and safe and potentially superior to conventional lipoinjection for facial recontouring. The authors have indicated no significant interest with commercial supporters.

The authors show convincing evidence of very dynamic remodeling of adipose tissue after nonvascularized grafting. The authors observed three zones from the periphery to the center of the graft: the surviving area (adipocytes survived), the regenerating area (adipocytes died, adipose-derived stromal cells survived, and dead adipocytes were replaced with new ones), and the necrotic area (both adipocytes and adipose-derived stromal cells died).

CD34 is frequently used as a marker of adipose-derived stem/stromal/progenitor cells (ASCs). However, CD34 expression in human ASCs (hASCs) decreases over time in culture, and the implications of this remain unclear. In this study, we sorted shortly-cultured hASCs into CD34+ and CD34- fractions and compared their biological functions. Results indicated that CD34+ hASCs were more proliferative and had a greater ability to form colonies. In contrast, CD34- cells showed a greater ability for differentiation into adipogenic and osteogenic lineages. Both CD34+ and CD34- cells showed similar abilities in migration and capillary formation in response to growth factors. Expression levels of endothelial progenitor markers (Flk-1, FLT1, and Tie-2) were higher in CD34+ cells, whereas those of pericyte markers (CD146, NG2, and alpha-smooth muscle actin) were higher in CD34- cells. Both CD34+ and CD34- cells showed similar expression levels of vascular endothelial growth factor and hepatocyte growth factor, although hypoxia affected the expression levels. Together these results suggest that CD34 expression in hASCs may correlate with replicative capacity, differentiation potentials, expression profiles of angiogenesis-related genes, and immaturity or stemness of the cells. Loss of CD34 expression may be related to the physiological process of commitment and/or differentiation from immature status into specific lineages such as adipose, bone, or smooth muscle.

Severe ischemia/hypoxia induces degenerative changes in adipose tissue and subsequent adaptive tissue remodeling. Adipocytes die easily under ischemic conditions, whereas adipose-derived stem/progenitor cells are activated and contribute to adipose tissue repair.

The authors' results indicate the differential structure and cellular composition of the two tissues, and significant tissue damage and progenitor yield deficiency in aspirated adipose tissue.

Many features of adipose tissue-specific stem/progenitor cells, such as physiological function and localization, have recently been examined. Adipose-tissue turnover is very slow and its perivascular progenitor cells differentiate into adipocytes in the next generation. The progenitor cells play important roles in physiological turnover, hyperplasia and atrophy of adipose tissue, as well as in incidental remodeling, such as postinjury repair. Adipose tissue has been used as an autologous filler for soft tissue defects, despite unpredictable clinical results and a low rate of graft survival, which may be due to the relative deficiency of progenitor cells in graft materials. A novel transplantation strategy, termed cell-assisted lipotransfer, involves the enrichment of adipose progenitor cells in grafts; preliminary results suggest this approach to be safe and effective.

Breast enhancement with artificial implants is one of the most frequently performed cosmetic surgeries but is associated with various complications, such as capsular contracture, that lead to implant removal or replacement at a relatively high rate. For replacement, we used transplantation of progenitor-supplemented adipose tissue (cell-assisted lipotransfer; CAL) in 15 patients. The stromal vascular fraction containing adipose tissue progenitor cells obtained from liposuction aspirates was used to enrich for progenitor cells in the graft. Overall, clinical results were very satisfactory, and no major abnormalities were seen on magnetic resonance imaging or mammogram after 12 months. Postoperative atrophy of injected fat was minimal and did not change substantially after 2 months. Surviving fat volume at 12 months was 155 +/- 50 mL (Right; mean +/- SD) and 143 +/- 80 mL (Left) following lipoinjection from an initial mean of 264 mL. These preliminary results suggest that CAL is a suitable methodology for the replacement of breast implants.

Platelet-rich plasma (PRP) has been clinically used as an easily prepared growth factor cocktail that can promote wound healing, angiogenesis, and tissue remodeling. However, the therapeutic effects of PRP are still controversial, due partly to the lack of optimized and standardized preparation protocols. We used whole blood (WB) samples to optimize the preparation protocols for PRP, white blood cell-containing (W-PRP), platelet-concentrated plasma (PCP), and noncoagulating platelet-derived factor concentrate (PFC). PRP and W-PRP were most efficiently collected by 10 min centrifugation in a 15-mL conical tube at 230-270 g and 70 g, respectively. To prepare PCP, platelets were precipitated by centrifugation of PRP at >2300 g, 90% of supernatant plasma was removed, and the platelets were resuspended. For preparation of noncoagulating PFC, the supernatant was replaced with one-tenth volume of saline, followed by platelet activation with thrombin. Platelet (before activation) and platelet-derived growth factor (PDGF)-BB (after activation) concentrations in PCP were approximately 20 times greater than those in WB, whereas PFC contained a 20-times greater concentration of platelets before platelet activation and a 50-times greater concentration of PDGF-BB without formation of a fibrin gel after platelet activation than WB. Surprisingly, total PDGF-BB content in the PFC was twice that of activated WB, which suggested that a substantial portion of the PDGF-BB became trapped in the fibrin glue, and replacement of plasma with saline is crucial for maximization of platelet-derived factors. As an anticoagulant, ethylene di-amine tetra-acetic acid disodium inhibited platelet aggregation more efficiently than acid citrate dextrose solution, resulting in higher nonaggregated platelet yield and final PDGF-BB content. These results increase our understanding of how to optimize and standardize preparation of platelet-derived factors at maximum concentrations.