Chao-Wei Huang

Sustained immobilization of growth factor proteins based on functionalized parylenes.

Protein molecules immobilized on biomaterial surfaces are performed based on oriented conjugation or replaced mimicking peptides. The sustainable immobilization of growth factor proteins using functionalized parylene coatings is demonstrated in this study. Site-specific and nonspecific immobilization approaches are realized to conjugate bone morphogenetic protein (BMP-2). The binding affinities and conformational changes of BMP-2 are confirmed by QCM and SPR characterizations. Osteoinduction of stem cells is examined by ALP activity on the BMP-2 modified surfaces. Finally, immobilizations and equally sustained biological functions of vascular endothelial growth factor (VEGF) and a mimicking peptide of KLTWQELYQLKYKG (QK) are also examined and confirmed.

Role of n-3 Polyunsaturated Fatty Acids in Ameliorating the Obesity-Induced Metabolic Syndrome in Animal Models and Humans

The incidence of obesity and its comorbidities, such as insulin resistance and type II diabetes, are increasing dramatically, perhaps caused by the change in the fatty acid composition of common human diets. Adipose tissue plays a role as the major energy reservoir in the body. An excess of adipose mass accumulation caused by chronic positive energy balance results in obesity. The n-3 polyunsaturated fatty acids (n-3 PUFA), DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) exert numerous beneficial effects to maintain physiological homeostasis. In the current review, the physiology of n-3 PUFA effects in the body is delineated from studies conducted in both human and animal experiments. Although mechanistic studies in human are limited, numerous studies conducted in animals and models in vitro provide potential molecular mechanisms of the effects of these fatty acids. Three aspects of n-3 PUFA in adipocyte regulation are discussed: (1) lipid metabolism, including adipocyte differentiation, lipolysis and lipogenesis; (2) energy expenditure, such as mitochondrial and peroxisomal fatty acid β-oxidation; and (3) inflammation, including adipokines and specialized pro-resolving lipid mediators. Additionally, the mechanisms by which n-3 PUFA regulate gene expression are highlighted. The beneficial effects of n-3 PUFA may help to reduce the incidence of obesity and its comorbidities.

Porcine Adiponectin Receptor 1 Transgene Resists High-fat/Sucrose Diet-Induced Weight Gain, Hepatosteatosis and Insulin Resistance in Mice

Adiponectin and its receptors have been demonstrated to play important roles in regulating glucose and lipid metabolism in mice. Obesity, type II diabetes and cardiovascular disease are highly correlated with down-regulated adiponectin signaling. In this study, we generated mice overexpressing the porcine Adipor1 transgene (pAdipor1) to study its beneficial effects in metabolic syndromes as expressed in diet-induced obesity, hepatosteatosis and insulin resistance. Wild-type (WT) and pAdipor1 transgenic mice were fed ad libitum with a standard chow diet (Chow) or a high-fat/sucrose diet (HFSD) for 24 weeks, beginning at 6 to 7 weeks of age. There were 12 mice per genetic/diet/sex group. When challenged with HFSD to induce obesity, the pAdipor1 transgenic mice resisted development of weight gain, hepatosteatosis and insulin resistance. These mice had lowered plasma adiponectin, triglyceride and glycerol concentrations compared to WT mice. Moreover, we found that (indicated by mRNA levels) fatty acid oxidation was enhanced in skeletal muscle and adipose tissue, and liver lipogenesis was inhibited. The pAdipor1 transgene also restored HFSD-reduced phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose transporter 4 mRNA in the adipose tissues, implying that the increased Pck1 may promote glyceroneogenesis to reduce glucose intolerance and thus activate the flux of glyceride-glycerol to resist diet-induced weight gain in the adipose tissues. Taken together, we demonstrated that pAdipor1 can prevent diet-induced weight gain and insulin resistance. Our findings may provide potential therapeutic strategies for treating metabolic syndromes and obesity, such as treatment with an ADIPOR1 agonist or activation of Adipor1 downstream targets.

Controlling multi-function of biomaterials interfaces based on multiple and competing adsorption of functional proteins.

Multifunctional biomaterial surfaces can be created by controlling the competing adsorption of multiple proteins. To demonstrate this concept, bone morphogenetic protein 2 (BMP-2) and fibronectin were adsorbed to the hydrophobic surface of polychloro-para-xylylene. The resulting adsorption properties on the surface depended on the dimensional and steric characteristics of the selected protein molecule, the degree of denaturation of the adsorbed proteins, the associated adsorption of interphase water molecules within the protein layers, and the aggregation of proteins in a planar direction with respect to the adsorbent surface. Additionally, a defined surface composition was formed by the competing adsorption of multiple proteins, and this surface composition was directly linked to the composition of the protein mixture in the solution phase. Although the mechanism of this complex competing adsorption process is not fully understood, the adsorbed proteins were irreversibly adsorbed and were unaffected by the further adsorption of homologous or heterologous proteins. Moreover, synergistic biological activities, including cell osteogenesis and proliferation independently and specifically induced by BMP-2 or fibronectin, were observed on the modified surface, and these biological activities were positively correlated with the surface composition of the multiple adsorbed proteins. These results provide insights and important design parameters for prospective biomaterials and biointerfaces for (multi)functional modifications. The ability to control protein/interface properties will be beneficial for the processing of biomaterials for clinical applications and industrial products.

Vapor-based coatings for antibacterial and osteogenic functionalization and the immunological compatibility

The immobilization of biofunctional molecules to biomaterial surfaces has enabled and expanded the versatility of currently available biomaterials to a wider range of applications. In addition, immobilized biomolecules offer modified surfaces that allow the use of smaller amounts of potentially harmful substances or prevent overdose, while the exhibited biological functions remain persistently effective. Surface concentrations of chlorhexidine (CHX) (1.40±0.08×10(-9)mol·cm(-2)) and bone morphogenetic protein 2 (BMP-2) (1.51±0.08×10(-11)mol·cm(-2)) immobilized molecules were determined in this study, and their specific biological functions in terms of antibacterial activity and osteogenesis potency, respectively, were demonstrated to be unambiguously effective. Immobilization exploits the use of vapor-based poly-p-xylylenes, which exhibit excellent biocompatibility and wide applicability for various substrate materials. This technique represents a practical and economical approach for the manufacture of certain industrial products. Furthermore, a minimal degree of macrophage activation was indicated on the modified surfaces via insignificant morphological changes and low levels of adverse inflammatory signals, including suppressed production of the pro-inflammatory cytokines IL-1β and TNF-α as well as nitric oxide (NO). The results and the modification strategy illustrate a concept for designing prospective biomaterial surfaces such that the manipulation employed to elicit targeted biological responses does not compromise immunological compatibility.

Enhanced bone morphogenic property of parylene-C

The ability to induce osteointegration was introduced to a parylene-C surface via the simple and intuitive process of protein adsorption mediated by hydrophobic interactions. In this way, bone morphogenetic protein (BMP)-2, fibronectin, and platelet-rich plasma (PRP) could be immobilized on parylene-C surfaces. This approach alleviates concerns related to the use of potentially harmful substances in parylene-C modification processes. The adsorbed protein molecules were quantitatively characterized with respect to adsorption efficacy and binding affinity, and the important biological activities of the proteins were also examined using both early and late markers of osteogenetic activity, including alkaline phosphatase expression, calcium mineralization and marker gene expression. Additionally, the adsorbed PRP exhibited potential as a substitute for expensive recombinant growth factors by effectively inducing comparable osteogenetic activity. In addition to the excellent biocompatibility of parylene-C and its ability to coat a wide variety of substrate materials, the modification of parylene-C via protein adsorption provides unlimited possibilities for installing specific biological functions, expanding the potential applications of this material to include various biointerface platforms.