Preparation and characterization of collagen microspheres for sustained release of VEGF

Abstract

In this study, we prepared injectable collagen microspheres for the sustained delivery of recombinant human vascular endothelial growth factor (rhVEGF) for tissue engineering. Collagen solution was formed into microspheres under a water-in-oil emulsion condition, followed by crosslinking with water-soluble carbodiimide. Various sizes of collagen microspheres in the range of 1-30 mum diameters could be obtained by controlling the surfactant concentration and rotating speed of the emulsified mixture. Particle size proportionally decreased with increasing the rotating speed (1.8 mum per 100 rpm increase in the range of 300-1,200 rpm) and surfactant concentration (3.1 mum per 0.1% increase in the range of 0.1-0.5%). The collagen microspheres showed a slight positive charge of 8.86 and 3.15 mV in phosphate-buffered saline and culture medium, respectively. Release study showed the sustained release of rhVEGF for 4 weeks. Released rhVEGF was able to induce capillary formation of human umbilical vein endothelial cells, indicating the maintenance of rhVEGF bioactivity after release. In conclusion, the results suggest that the collagen microspheres have potential for sustained release of rhVEGF.

Microporous Nano-hydroxyapatite/collagen/phosphatidylserine Scaffolds Embedding Collagen Microparticles for Controlled Drug Delivery in Bone Tissue Engineering

“…Drug loaded delivery system is considered an emerging alternative for the regeneration of bone defects 1 . Such drug provide readily available bioactivity facilitating bone ingrowth, Steroidal saponins (SS) has been demonstrated to promote the proliferation of osteoblasts.…”

Biomimetic composite microspheres of collagen/chitosan/nano-hydroxyapatite: In-situ synthesis and characterization

“…3. The reduced crystallinity of HA in the COL/CS/HA composite microspheres with 40 wt.% HA might be attributed that the rate of the diffusion-controlled reaction between Ca 2+ and PO 4 3− ions as well as the growth rate of the HA nucleus decreased with the increase of the ion concentrations, which eventually led to the generation of smaller sized HA particles at the given experimental conditions.…”

“…Collagen (COL), as one of the universal templates in biomineralization [1,2], has many unique advantages including excellent biocompatibility, desirable biodegradability and preferable cellular affinity for various biomedical applications [3][4][5]. Moreover, the mechanical strength and bioactivity of the collagen materials can be efficiently improved by hybridization with a bioactive inorganic phase, hydroxyapatite (HA), which makes the collagen/HA composites even more attractive for bone tissue regeneration [6,7].…”

The Use of Micro- and Nanospheres as Functional Components for Bone Tissue Regeneration

“…The resulting microspheres have been used as microcarriers for bioactive factors in bone regeneration, [30][31][32][33] which showed controllable drug release kinetics by tailoring the collagen crosslinking density or by introducing bridging forces (such as electrostatic interactions) between biomolecules and the microsphere polymer network. 30,32 Nevertheless, only limited progress in collagen microspheres for tissue engineering has been made most likely owing to their poor mechanical stability, suboptimal processing conditions, and possible denaturation on processing. 26,27 To address this, Chan et al developed reconstituted collagen-MSC microspheres based on the self-assembly between collagen and MSCs, which exhibited desired stability as cell delivery carriers for tissue engineering.…”