Stromal vascular fraction cells plus sustained release VEGF/Ang-1-PLGA microspheres improve fat graft survival in mice.

Autologous fat transplantation is increasingly applied in plastic and reconstructive surgery. Stromal vascular fraction cells (SVFs) combined with angiogenic factors, such as VEGF (vascular endothelial growth factor A) and Ang-1 (angiogenin-1), can improve angiogenesis, which is a critical factor for graft survival. However, direct transplant with such a mixture is insufficient owing to the short half-life of angiogenic factors. In this study, we evaluated whether a double sustained release system of VEGF/ANG-1-PLGA (poly (lactic-co-glycolic acid)) microspheres plus SVFs can improve angiogenesis and graft survival after autologous fat transplantation. VEGF/ANG-1-PLGA-sustained release microspheres were fabricated by a modified double emulsion-solvent evaporation technique. Human aspirated fat was mixed with SVF suspension plus VEGF/ANG-1 sustained release microspheres (Group C), SVF suspension (Group B) alone, or Dulbecco's modified Eagle's medium as the control (Group A). Eighteen immunocompromised nude mice were injected with these three mixtures subcutaneously at random positions. After 8 weeks, the mean volume of grafts was greater in the SVFs plus VEGF/ANG-1-PLGA group than in the control and SVFs groups (1.08 ± 0.069 ml vs. 0.62 ± 0.036 ml, and 0.83 ± 0.059 ml, respectively). Histological assessments showed that lower fibrosis, but greater microvascular density in the SVFs plus VEGF/ANG-1-PLGA group than in the other groups, though the SVFs group also had an appropriate capillary density and reduced fibrosis. Our findings indicate that SVFs plus VEGF/ANG-1-PLGA-sustained release microspheres can improve angiogenesis and graft survival after autologous fat transplantation.

Plasmonic color generation and refractive index sensing with three-dimensional air-gap nanocavities.

Three-dimensional (3D) air-gap metal-coated nanocavities with tunable geometries, changeable heights, and improved smoothness are fabricated by combining electron beam lithography (EBL), ultra dilute hydrofluoric acid solution wet etching (UDHFE), and metal magnetron sputtering technologies. With different shapes, heights, and separations of the nanocavities, the strong electromagnetic resonances inside the nanocavities are changed in different extent, resulting in broad gamut and sophisticated plasmonic color generation. The nanocavities-based metasurface is also used to construct a real-time and label-free refractive index sensor with 372 nm/RIU sensitivity, which shows distinct colorimetric change between different mediums. This nanocavities may find extensive potential applications in high-fidelity color printing, high-density information storage, and on-chip colorimetric label-free biomedical sensing.

Effects of VEGF-ANG-1-PLA nano-sustained release microspheres on proliferation and differentiation of ADSCs.

The improvement of fat graft viability might depend on the presence of multipotent resident adipose derived stem cells (ADSCs) which is the important component of stromal vascular fraction (SVF). Vascular endothelial growth factor (VEGF) and angiogenin-1 (Ang-1) are responsible for neovascularization. However, their half-life is too short to produce a biological effect. We thus investigated whether VEGF-ANG-1-polylactic acid (PLA) microspheres could enhance the angiogenic properties of ADSCs. PLA microspheres containing VEGF and ANG-1 were prepared by in vitro ultrasonic emulsification and characterized according to their encapsulation efficiency (EE), drug-loading rate (DL), particle size, and drug release. The systemic toxicity of empty loaded nanospheres (NPs) and the ability of these microspheres to promote the proliferation and differentiation of ADSCs were evaluated. The EE and DL were above 86% and 0.0288%, respectively [corrected].The drug release was completed after 20 days. Systemic toxicity was verified in ADSCs that received the unloaded NPs. It was observed that ADSCs treated with VEGF-ANG-1-PLA microspheres had an increase in the proliferation and the number of CD31 positive cells. ADSCs proliferation and differentiation toward endothelial cells (ECs) could be enhanced by the addition of VEGF-ANG-1-PLA nano-sustained release microspheres.

Rapamycin Promotes the Survival and Adipogenesis of Ischemia-Challenged Adipose Derived Stem Cells by Improving Autophagy.

BACKGROUND/AIMS: Ischemia is one of the main causes of the high rate of absorption of transplanted autologous fat. Autophagy allows cells to survive by providing energy under starvation. Rapamycin has been found to play a role in promoting autophagy. In this study, we investigated whether rapamycin participates in the survival and adipogenesis of ischemia-challenged adipose-derived stem cells (ADSCs) by regulating autophagy. METHODS: Before the cells were exposed to oxygen-glucose deprivation (OGD), a simulated ischemic microenvironment, the level of autophagy was reduced or increased by lentiviral transfection with short hairpin RNA targeting microtubule-associated protein 1-light chain 3 gene (shRNA-LC3) or treatment with rapamycin, respectively. The level of autophagy was assessed by western blotting, transmission electron microscopythen the apoptosis ratio was determined through terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and flow cytometry. Adipogenesis was further evaluated by oil red O staining and the expressions level of some specific proteins for adipocytes. RESULTS: shRNA-LC3 and rapamycin treatment effectively decreased and improved the level of autophagy in cells with or without OGD challenge, respectively. In addition, autophagy inhibition increased the apoptosis rate and activated caspase-3 expression level in response to OGD, and these were markedly inhibited by rapamycin preconditioning. During adipogenesis, autophagy inhibition decreased not only oil droplet accumulation but also lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor gamma (PPARγ) expression in cells with or without OGD challenge. However, autophagy promotion by rapamycin increased oil droplet accumulation and LPL and PPARγ expression. CONCLUSIONS: Rapamycin may promote the survival and adipogenesis of ischemia-challenged ADSCs by upregulating autophagy.

Autologous decellularized extracellular matrix protects against H2O2-induced senescence and aging in adipose-derived stem cells and stimulates proliferation in vitro.

Background: Adipose-derived stem cells have attracted significant interest, especially in stem cell therapy and regenerative medicine. However, these cells undergo gradual premature senescence in long-term cultures, which are essential for clinical applications that require cell-assisted lipotransfer or tissue repair. Methods: Since the extracellular matrix forms the microenvironment around stem cells in vitro and regulates self-renewal and multipotency in part by slowing down stem cell aging, we evaluated its potential to protect against senescence, using H2O2-induced adipose-derived stem cells as a model. Results: We found that supplementing cultures with decellularized extracellular matrix harvested from the same cells significantly promotes proliferation and reverses signs of senescence, including decreased multipotency, increased expression of senescence-associated ß-galactosidase, and accumulation of reactive oxygen species. Conclusion: These findings suggest a novel approach in which an autologous decellularized extracellular matrix is used to prevent cellular senescence to enable the use of adipose-derived stem cells in regenerative medicine.

Prevalence, Characteristics, and Outcome of Cow's Milk Protein Allergy in Chinese Infants: A Population-Based Survey.

BACKGROUND: Cow's milk protein allergy (CMPA) is commonly seen in children. There have been no reports of the true prevalence of CMPA in Chinese infants. The aim of this population-based study is to determine the prevalence, clinical characteristics, and outcome of CMPA in Chinese infants. METHODS: We carried out a prospective survey in 7 participating hospitals throughout southern China. We included infants ≤12 months of age during the survey. For those suspected of CMPA, oral food challenge with cow's milk protein (CMP) was performed. A follow-up telephone interview was conducted at 12 months after the diagnosis to assess the clinical outcome of CMPA. RESULTS: A total of 9910 questionnaire surveys were distributed and 7364 (74.3%) were returned. The eligible survey number of surveys was 6768 (91.9%). A total of 182 infants was confirmed with CMPA, including 13 with anaphylactic reactions, 28 with clinical symptoms and serum immunoglobulin E (sIgE) >3.5 IU/mL, and 141 with positive CMP challenge test. The prevalence of CMPA was 2.69%. Infants with confirmed CMPA had significantly stronger family history of either 1 or both parents with food allergy, higher Cesarean section rate, and lower rate of breastfeeding, compared with those without CMPA. At 12-month telephone follow-up of 176 CMPA infants, 136 infants (77.3%) had become tolerant to CMP. CONCLUSIONS: The prevalence of CMPA was 2.69%. CMPA infants had a strong family history of food allergy and atopy. Both Cesarean delivery and formula feeding were risk factors for CMPA. At 12-month follow-up, the majority of CMPA infants had become tolerant to CMP.

Large-Scale Fabrication of Ultrasensitive and Uniform Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Pesticides.

Technology transfer from laboratory into practical application needs to meet the demands of economic viability and operational simplicity. This paper reports a simple and convenient strategy to fabricate large-scale and ultrasensitive surface-enhanced Raman scattering (SERS) substrates. In this strategy, no toxic chemicals or sophisticated instruments are required to fabricate the SERS substrates. On one hand, Ag nanoparticles (NPs) with relatively uniform size were synthesized using the modified Tollens method, which employs an ultra-low concentration of Ag⁺ and excessive amounts of glucose as a reducing agent. On the other hand, when a drop of the colloidal Ag NPs dries on a horizontal solid surface, the droplet becomes ropy, turns into a layered structure under gravity, and hardens. During evaporation, capillary flow was burdened by viscidity resistance from the ropy glucose solution. Thus, the coffee-ring effect is eliminated, leading to a uniform deposition of Ag NPs. With this method, flat Ag NPs-based SERS active films were formed in array-well plates defined by hole-shaped polydimethylsiloxane (PDMS) structures bonded on glass substrates, which were made for convenient detection. The strong SERS activity of these substrates allowed us to reach detection limits down to 10-14 M of Rhodamine 6 G and 10-10 M of thiram (pesticide).

[Research progress of growth factor sustained-release microspheres in fat transplantation].

Objective: To review the research progress of growth factor sustained-release microspheres in fat transplantation. Methods: The recently published 1iterature at home and abroad related the growth factor sustained-release microspheres in fat transplantation was reviewed and analyzed. Results: The sustained-release microsphere carrier materials include natural polymer materials and synthetic polymer materials.The sustained-release complexes of different microsphere materials with different growth factors can promote the vascularization of transplanted fat in a timely manner, improve the survival rate of grafts, and reduce the incidence of complications such as liquefaction, calcification, and necrosis. Conclusion: The growth factor sustained-release microspheres have the characteristics of persistence and controllability, which is a research hotspot in the field of fat transplantation and has broad application prospects.