Engineered stem cell niche matrices for rotator cuff tendon regenerative engineering.

Rotator cuff (RC) tears represent a large proportion of musculoskeletal injuries attended to at the clinic and thereby make RC repair surgeries one of the most widely performed musculoskeletal procedures. Despite the high incidence rate of RC tears, operative treatments have provided minimal functional gains and suffer from high re-tear rates. The hypocellular nature of tendon tissue poses a limited capacity for regeneration.

Polyphosphazene functionalized polyester fiber matrices for tendon tissue engineering: in vitro evaluation with human mesenchymal stem cells.

Poly[(ethyl alanato)(1)(p-methyl phenoxy)(1)] phosphazene (PNEA-mPh) was used to modify the surface of electrospun poly(ε-caprolactone) (PCL) nanofiber matrices having an average fiber diameter of 3000 ± 1700 nm for the purpose of tendon tissue engineering and augmentation. This study reports the effect of polyphosphazene surface functionalization on human mesenchymal stem cell (hMSC) adhesion, cell-construct infiltration, proliferation and tendon differentiation, as well as long term cellular construct mechanical properties. PCL fiber matrices functionalized with PNEA-mPh acquired a rougher surface morphology and led to enhanced cell adhesion as well as superior cell-construct infiltration when compared to smooth PCL fiber matrices.

Design and optimization of polyphosphazene functionalized fiber matrices for soft tissue regeneration.

Electrospun polycaprolactone nanofiber matrices surface functionalized with poly[(ethyl alanato), (p-methyl phenoxy),] phosphazene were fabricated for the purpose of soft skeletal tissue regeneration. This preliminary study reports the effect of fiber diameter and polyphosphazene surface functionalization on significant scaffold properties such as morphology, surface hydrophilicity, porosity, tensile properties, human mesenchymal stem cell adhesion and proliferation. Six fiber matrices comprised of average fiber diameters in the range of 400-500, 900-1000, 1400-1500, 1900-2000, 2900-3000 and 3900-4000 nm were considered for primary evaluation.

Miscibility of choline-substituted polyphosphazenes with PLGA and osteoblast activity on resulting blends.

The preparation of phosphazene tissue engineering scaffolds with bioactive side groups has been accomplished using the biological buffer, choline chloride. Mixed-substituent phosphazene cyclic trimers (as model systems) and polymers with choline chloride and glycine ethyl ester, alanine ethyl ester, valine ethyl ester, or phenylalanine ethyl ester were synthesized. Two different synthetic protocols were examined.

Stepwise conversion of two pyrrole moieties of octaethylporphyrin to pyridin-3-ones: synthesis, mass spectral, and photophysical properties of mono and bis(oxypyri)porphyrins.

Free-base octaethylporphyrin (OEP) was converted in two steps (beta,beta'-dihydroxylation and oxidative diol cleavage with concomitant aldol condensation) to the corresponding oxypyriporphyrin. This conversion was previously described to be applicable only to the Ni(II) complex of OEP. Modified diol cleavage conditions made this reaction sequence now applicable to free-base OEP.