Tissue Engineering and Drug Delivery

Tissue Engineering and Drug Delivery

Tissue Engineering Demonstration

3D Bio-printer Demonstration

3D Bioreactor Demonstration

Chang PC, Chong LY, Dovban AS, Lim LP, Lim JC, Kuo MY, Wang CH. Sequential platelet-derived growth factor-simvastatin release promotes dentoalveolar regeneration. Tissue Eng Part A. 2014 Jan;20(1-2):356-64.

Abstract

OBJECTIVES:

Timely augmentation of the physiological events of dentoalveolar repair is a prerequisite for the optimization of the outcome of regeneration. This study aimed to develop a treatment strategy to promote dentoalveolar regeneration by the combined delivery of the early mitogenic factor platelet-derived growth factor (PDGF) and the late osteogenic differentiation factor simvastatin.

MATERIALS AND METHODS:

By using the coaxial electrohydrodynamic atomization technique, PDGF and simvastatin were encapsulated in a double-walled poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) (PDLLA-PLGA) microspheres in five different modes: microspheres encapsulating bovine serum albumin (BB), PDGF alone (XP), simvastatin alone (SB), PDGF-in-core and simvastatin-in-shell (PS), and simvastatin-in-core and PDGF-in-shell (SP). The microspheres were characterized using scanning electronic microscopy, and the in vitro release profile was evaluated. Microspheres were delivered to fill large osteotomy sites on rat maxillae for 14 and 28 days, and the outcome of regeneration was evaluated by microcomputed tomography and histological assessments.

RESULTS:

Uniform 20-μm controlled release microspheres were successfully fabricated. Parallel PDGF-simvastatin release was noted in the PS group, and the fast release of PDGF followed by the slow release of simvastatin was noted in the SP group. The promotion of osteogenesis was observed in XP, PS, and SP groups at day 14, whereas the SP group demonstrated the greatest bone fill, trabecular numbers, and thickest trabeculae. Bone bridging was evident in the PS and SP group, with significantly increased osteoblasts in the SP group, and osteoclastic cell recruitment was promoted in all bioactive molecule-treated groups. At day 28, osteogenesis was promoted in all bioactive molecule-treated groups. Initial corticalization was noted in the XP, PS, and SP groups. Osteoblasts appeared to be decreased in all groups, and significantly, a greater osteoclastic cell recruitment was noted in the SB and SP groups.

CONCLUSIONS:

Both PDGF and simvastatin facilitate dentoalveolar regeneration, and sequential PDGF-simvastatin release (SP group) further accelerated the regeneration process through the enhancement of osteoblastogenesis and the promotion of bone maturation.

Histological observations. The image was selected from the center of the osteotomy (dashed box in the upper panel) in a representative section of each group at (A) day 14 and (B) day 28. The asterisks indicate the residual microspheres, and the arrows indicate the reversal lines in the bone matrix (hematoxylin and eosin stain; magnification, 200×). M2, maxillary second molar; M3, maxillary third molar; NB, new bone.

X.H. Zhu, C.H. Wang, Y.W. Tong, “Growing tissue-like constructs with Hep3B/HepG2 liver cells on PHBV microspheres of different sizes” Journal of Biomedical Materials Research: Part B: Applied Biomaterials, 82B, 7-16 (2007)

Abstract

In this study, an oil-in-water emulsion solvent evaporation technique was used to fabricate poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 8% PHV), microspheres as scaffold, to guide liver cell growth. Human hepatoma cell lines, HepG2 and Hep3B, were cultured in vitro on both the microspheres and polymer films. SEM and optical microscope images showed that multilayer cells were formed among the microspheres to bridge them together and developed into cell-construct aggregates after 1 week of culture. MTT results showed that the cell proliferation on the microspheres was more than two times higher than that on the films after 12 days of culture. The cells seeded on microspheres secreted albumin 2–4 times more than that on the positive control after 1 week of culture, which indicated that this hepatic function was greatly improved by the aggregation of cells on microspheres. Although HepG2 failed to express P-450 activity, this hepatic function was preserved when Hep3B cultured on microspheres. All the results indicated that PHBV microspheres are appropriate scaffolds for liver tissue engineering.

Optical micrographs of HepG2 cells growth on M1 after (a) 2 days, (b) 4 days, (c) 8 days, and (d) 14 days of culture, (e) HepG2 growth on M2 after 14 days of culture, (f) HepG2 growth on M3 after 14 days of culture; (g,h) CLSM images of Hep3B cells growth on M1 after 14 days of culture

H. Nie, M.L. Ho, C.K. Wang , C.H. Wang, and Y.C. Fu ” BMP-2 plasmid loaded PLGA/HAp composite scaffolds for treatment of bone defects in nude mice”, Biomaterials, 30, 892-901 (2009).

Abstract

We studied three different types of scaffolds, encapsulating bone morphogenetic protein-2 (BMP-2) plasmid, in terms of their performances in bone regeneration in nude mice. The plasmid was loaded into fibrous matrices in three different ways: coating of naked DNA (Group A) or DNA/chitosan nanoparticles (Group B) onto scaffolds after fiber fabrication by dripping, and encapsulation of DNA/chitosan nanoparticles into scaffold by mixing them with PLGA/DCM solution before fiber fabrication (Group C). Their individual performances were examined by soft X-ray observation, histological analysis and immunostaining of bone tissue. In addition, the BMP-2 protein concentration and alkaline phosphatase (ALP) activity in serum were monitored. The results revealed that the bioactivity of BMP-2 plasmid released from all three kinds of scaffolds was well maintained; this eventually helped improve the healing of segmental defects in vivo. Interestingly, the three kinds of scaffolds released DNA or DNA nanoparticles in different modes and their performances in bone healing were diverse. These observations demonstrate that the in vivo performance of these newly developed DNA delivery devices correlates well with their in vitro release profiles.

Radiographs of nude mice tibias after 2 and 4 weeks of implantation of scaffolds. Bone fragment without implantation of any scaffold is denoted as control and white arrows identify bone defects

Hemin Nie, Beng Wee Soh, Yin-Chih Fu, Chi-Hwa Wang, “Three-Dimensional Fibrous PLGA/HAp Composite Scaffold for BMP-2 Delivery”, Biotechnology and Bioengineering

Abstract

A protein loaded three dimensional scaffold can be used for protein delivery and bone tissue regeneration. The main objective of this project was to develop recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded PLGA/HAp composite fibrous scaffolds through a promising fabrication technique, electrospinning. In vitro release of BMP-2 from these scaffolds, and the attachment ability and viability of marrow derived messenchymal stem cells (MSCs) in the presence of the scaffolds were investigated. The PLGA/HAp composite scaffolds developed in this study exhibit good morphology and it was observed that HAp nanoparticles were homogeneously dispersed inside PLGA matrix within the scaffold. The composite scaffolds allowed sustained (2-8 weeks) release of BMP-2 whose release rate was accelerated with increasing HAp content. It was also shown that BMP-2 protein successfully maintained its integrity and natural conformations after undergoing the process of electrospinning. Cell culture experiments showed that the encapsulation of HAp could enhance cell attachment to scaffolds and lower cytotoxicity