PI Name: Tien-Min Gabriel Chu, PhD, DDS
Lab Name: Chu Lab
PI Email: tgchu@iu.edu
Lab Room #: DS 509
Lab Members: Parham Karimi
Major Research Project Description
Dr. Chu’s early research focus was on the development of rapid-prototyping materials for ceramic tissue engineering scaffolds. His paper published in 2003 (PMID: 11808536) contained one of the earliest demonstrations of hydroxyapatite scaffolds fabricated using a rapid-prototyping technique and evaluated in a minipig mandible model. He further extended his research to include other biomaterials for tissue engineering scaffolds including dicalcium phosphate dihydrate, bioactive glass, polypropylene fumarate/tricalcium phosphate, and thiol-acrylate hydrogels.
His paper published in 2007 (PMCID: PMC1986795) was one of the earliest models of a modular scaffold design that demonstrates the concept of using multiple compartments in the scaffold for bone regeneration in load-bearing areas. He has evaluated these scaffolds in craniofacial and long bone defects models in various animal species, including mice, rats, rabbits, dogs, and miniature pigs. His other contribution is in the research of calcium phosphate (CaP) cement that can function as a protein carrier in the scaffold. The existing CaP formulated from monocalcium phosphate (MCPM) and tricalcium phosphate (TCP) has a slow degradation rate and can potentially prevent new tissue formation. In a series of experiments to further improve the degradation property of the CaP cement, Dr. Chu’s laboratory demonstrated that by replacing TCP with hydroxyapatite (HA): 1) a cement with appropriate mechanical properties can be achieved (PMID: 19349655); 2) the setting time and mechanical properties can be tailored by using sulfuric acid and sodium pyrophosphate as setting regulators (PMID: 22101069); and 3) the new formulation shows a faster degradation rate through a rapid conversion of the cement back to HA (PMID: 22323239, PMCID: PMC3649140).
Finally, he also contributes to the understanding of the microstructure and optical properties of all-ceramic dental restorative materials (PMID: 26076831, PMID: 34116838). His research has been funded by the National Institute of Health, the Department of Defense, foundations, and private industries. He has published more than eighty papers and co-authored five US patents.
Photographs
Figure 1. Representative histological images of segmental defects in the (A) control and (B,C) rhBMP groups at six weeks post-operatively. Sections are stained with McNeal’s tetrachrome, which stains bone black. (A) Segmental defects in the control group demonstrated cartilaginous union, whereas (B) defects in the BMP group were bridged by mineralized callus that (C) invaded the side hole and was on the surface of the scaffold, indicating scaffold osteoconductivity. Inflammatory cells were not present in either scaffold group. (D) By 16-weeks post-operatively in the BMP group, the osteoconductivity of the scaffold is evident by the formation of new bone on its surfaces. * = original cortex of the femoral diaphysis, # = weight bearing biodegradable scaffold, † = cartilaginous tissue, ‡ = mineralized callus, § = side hole within the scaffold, ║ = residual dicalcium phosphate dihydrate cement carrying rhBMP-2, ∆ = mineralized callus within the side hole and on the surface of the scaffold.
Figure 2. Representative external and cut-away images of segmental defects in the (A) control and (B) BMP groups, as assessed by microcomputed tomography at six weeks post-operatively. (A) Segmental defects in the control group had minimal bone surrounding the scaffold and the reparative callus did not bridge the defect. (B) In contrast, the BMP group had a continuous mineralized callus around the scaffold, and bridging trabeculae beneath the cortical layer of the callus were integrated with the scaffold, indicating scaffold osteoconductivity. (C) By 16-weeks post-operatively in the BMP-group, the bridging trabeculae had thickened and there is evidence of bone formation of bone on the surfaces of the scaffold, indicating scaffold osteoconductivity. * = original cortex of the femoral diaphysis, # = weight bearing biodegradable scaffold, † = mineralized callus, ‡ = side hole within the scaffold.