Peter X Ma

The scaffold is a porous three‐dimensional (3D) material that supports cell growth and tissue regeneration. Such 3D structures should be generated with simple techniques and nontoxic ingredients to mimic bio‐environment and facilitate tissue regeneration. In this work, simple but powerful techniques are demonstrated for the fabrication of lamellar and honeycomb‐mimic scaffolds with poly(L‐lactic acid). The honeycomb‐mimic scaffolds with tunable pore size ranging from 70 to 160 µm are fabricated by crystal needle‐guided thermally induced phase separation in a directional freezing apparatus. The compressive modulus of the honeycomb‐mimic scaffold is ≈4 times higher than that of scaffold with randomly oriented pore structure. The fabricated honeycomb‐mimic scaffold exhibits a hierarchical structure from nanofibers to micro‐/macro‐tubular structures. Pre‐osteoblast MC3T3‐E1 cells cultured on the …

Stimuli‐responsive domains capable of releasing loaded molecules, “on‐demand,” have garnered increasing attention due to their enhanced delivery, precision targeting, and decreased adverse effects. The development of an on‐demand delivery system that can be easily triggered by dental clinicians might have major roles in dental and oral tissue engineering. A series of random graft poly(NIPAm‐co‐HEMA‐Lactate) copolymers were synthesized using 95:5, 85:5, 60:40, and 40:60 ratios of thermosensitive NIPAm and HEMA‐poly lactate respectively then electrospun to produce nanofibrous scaffolds loaded with bovine serum albumin (BSA). Cumulative BSA release was assessed at 25C and 37°C. To appraise the use of scaffolds as on‐demand delivery systems, they were subjected to thermal changes in the form cooling and warming cycles during which BSA release was monitored. To confirm the triggered …

Gene therapy and gene delivery have drawn extensive attention in recent years especially when the COVID-19 mRNA vaccines were developed to prevent severe symptoms caused by the corona virus. Delivering genes, such as DNA and RNA into cells, is the crucial step for successful gene therapy and remains a bottleneck. To address this issue, vehicles (vectors) that can load and deliver genes into cells are developed, including viral and non-viral vectors. Although viral gene vectors have considerable transfection efficiency and lipid-based gene vectors become popular since the application of COVID-19 vaccines, their potential issues including immunologic and biological safety concerns limited their applications. Alternatively, polymeric gene vectors are safer, cheaper, and more versatile compared to viral and lipid-based vectors. In recent years, various polymeric gene vectors with well-designed molecules …

The aim of this study was to investigate the effect of short-term (3 days) preconditioning with pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) on proliferation and odontogenic differentiation of stem cells of apical papilla (SCAP) seeded on a 3D scaffold. Our results showed that while TNF-α preconditioning at various concentrations did not affect SCAP proliferation, it enhanced alkaline phosphatase (ALP) activity and mineralized matrix deposition in culture. Preconditioning SCAP using TNF-α at a concentration of about 1 ng/ml optimally enhanced odontogenic gene expression of SCAP in culture. Highly porous nanofibrous (NF) poly(l-lactic acid) (PLLA) scaffolds, with nanofiber features mimicking the environment of the extracellular matrix, were fabricated using a thermally induced phase separation method. TNF-α preconditioning of SCAP at 1 ng/ml promoted ALP activity, calcium deposition and …

Aim To investigate the potential of an ultrashort aromatic peptide hydrogelator integrated with hyaluronic acid (HA) to serve as a scaffold for bone regeneration. Materials and Methods Fluorenylmethyloxycarbonyl‐diphenylalanine (FmocFF)/HA hydrogel was prepared and characterized using microscopy and rheology. Osteogenic differentiation of MC3T3‐E1 preosteoblasts was investigated using Alizarin red, alkaline phosphatase and calcium deposition assays. In vivo, 5‐mm‐diameter calvarial critical‐sized defects were prepared in 20 Sprague–Dawley rats and filled with either FmocFF/HA hydrogel, deproteinized bovine bone mineral, FmocFF/Alginate hydrogel or left unfilled. Eight weeks after implantation, histology and micro‐computed tomography analyses were performed. Immunohistochemistry was performed in six rats to assess the hydrogel's immunomodulatory effect. Results A nanofibrous FmocFF …

In an example of a method for making a pulsatile delivery device, one type of charges are generated on a polymeric layer, and charges opposite the one type of charges are generated on a delivery layer including a film forming material and a predetermined substance dispersed throughout the film forming material. The charged polymeric and delivery layers are placed into contact to form a bi-layer structure. A stack with at least two bi-layer structures is formed so that the polymeric layers and the delivery layers are alternating throughout the stack. The stack is sealed so that one of the polymeric layers remains exposed.

Skeletal progenitor: collagen interactions are critical for bone development and regeneration. Both collagen-binding integrins and discoidin domain receptors (DDR1 and DDR2) function as collagen receptors in bone. Each receptor is activated by a distinct collagen sequence; GFOGER for integrins and GVMGFO for DDRs. Specific triple helical peptides containing each of these binding domains were evaluated for ability to stimulate DDR2 and integrin signaling and osteoblast differentiation. GVMGFO peptide stimulated DDR2 Y740 phosphorylation and osteoblast differentiation as measured by induction of osteoblast marker mRNAs and mineralization without affecting integrin activity. In contrast, GFOGER peptide stimulated focal adhesion kinase (FAK) Y397 phosphorylation, an early measure of integrin activation, and to a lesser extent osteoblast differentiation without affecting DDR2-P. Significantly, the …

Provided herein are biodegradable copolymers, methods of lactone polymerization, nanofibrous scaffolds, and methods of regenerating tissue.