Polyphenolic-modified cellulose acetate membrane for bone regeneration through immunomodulation.

To enhance the bioactivity of cellulosic derivatives has become an important strategy to promote their value for clinical applications. Herein, protocatechualdehyde (PCA), a polyphenolic molecule, was used to modify a cellulose acetate (CA) membrane by combining with metal ions to confer an immunomodulatory activity. The PCA-modified CA membrane has shown a significant radical scavenging activity, thereby suppressed the inflammatory response and created a favorable immune microenvironment for osteogenesis and mineralization. Moreover, addition of metal ions could further stimulate the osteogenic differentiation of stem cells and accelerate bone regeneration both in vitro and in vivo. This study may provide a strategy to promote the immunomodulatory activity of cellulose-based biomaterials for bone regeneration.

Polymeric antibacterial materials: design, platforms and applications.

Over the past decades, the morbidity and mortality caused by pathogen invasion remain stubbornly high even though medical care has increasingly improved worldwide. Besides, impacted by the ever-growing multidrug-resistant bacterial strains, the crisis owing to the abuse and misuse of antibiotics has been further exacerbated. Among the wide range of antibacterial strategies, polymeric antibacterial materials with diversified synthetic strategies exhibit unique advantages (e.g., their flexible structural design, processability and recyclability, tuneable platform construction, and safety) for extensive antibacterial fields as compared to low molecular weight organic or inorganic antibacterial materials. In this review, polymeric antibacterial materials are summarized in terms of four structure styles and the most representative material platforms to achieve specific antibacterial applications. The superiority and defects exhibited by various polymeric antibacterial materials are elucidated, and the design of various platforms to elevate their efficacy is also described. Moreover, the application scope of polymeric antibacterial materials is summarized with regard to tissue engineering, personal protection, and environmental security. In the last section, the subsequent challenges and direction of polymeric antibacterial materials are discussed. It is highly expected that this critical review will present an insight into the prospective development of antibacterial functional materials.

Poly(cystine-PCL) based pH/redox dual-responsive nanocarriers for enhanced tumor therapy.

Functional polymeric drug delivery systems have generated enormous interest due to their excellent features. This paper reports the development of a novel pH and redox dual-sensitive polymer for anticancer paclitaxel (PTX) delivery applications. The polymer was prepared by polycondensation of disulfide bond-containing dimethyl l-cystinate (Cys) and polycaprolactone (PCL) oligomer via a pH-responsive imine bond. Using the nanoprecipitation method, the polymer can be formulated as nanoparticles (poly(Cys-PCL)/PTX NPs) with a diameter less than 100 nm, as measured by TEM and DLS. The NPs release PTX significantly faster at mildly acidic pH and high concentrations of GSH, exhibiting almost no burst release under the physiological conditions of plasma. Notably, the NPs efficiently deliver PTX to the tumor cells, which was more cytotoxic to 4T1 cancer cells than the pure PTX alone. In vivo results reveal an excellent tumor inhibiting ability, good drug tolerability and biosafety of poly(Cys-PCL)/PTX NPs. Overall, the poly(Cys-PCL)/PTX NPs platform may have greater potential in enhancing cancer therapy.

Coculture of peripheral blood-derived mesenchymal stem cells and endothelial progenitor cells on strontium-doped calcium polyphosphate scaffolds to generate vascularized engineered bone.

Vascularization of engineered bone tissue is critical for ensuring its survival after implantation and it is the primary factor limiting its clinical use. A promising approach is to prevascularize bone grafts in vitro using endothelial progenitor cells (EPC) derived from peripheral blood. Typically, EPC are added together with mesenchymal stem cells (MSC) that differentiate into osteoblasts. One problem with this approach is how to promote traditional tissue engineering bone survival with a minimally invasive method. In this study, we examined the effectiveness of administering to stimulate the release of peripheral blood stem cells and their co-culturing system for generating prevascularized engineered bone. Cells were isolated by Ficoll density gradient centrifugation and identified as EPC and MSC based on morphology, surface markers, and functional analysis. EPC and MSC were cocultured in several different ratios, and cell morphology and tube formation were assessed by microscopy. Expression of osteogenesis and vascularization markers was quantified by enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction, and histochemical and immunofluorescence staining. Increasing the proportion of EPC in the coculture system led to greater tube formation and greater expression of the endothelial cell marker CD31. An EPC:MSC ratio of 75:25 gave the highest expression of osteogenesis and angiogenesis markers. Cocultures adhered to a three-dimensional scaffold of strontium-doped calcium polyphosphate and proliferated well. Our findings show that coculturing peripheral blood-derived EPC and MSC may prove useful for generating prevascularized bone tissue for clinical use.