Papers by Author: Julia M. Polak

Abstract: Historically the function of biomaterials has been to replace diseased, damaged and aged tissues. First generation biomaterials, including bio ceramics, were selected to be as inert as possible in order to minimize the thickness of interfacial scar tissue. Bioactive glasses provided an alternative from the 1970’s onward; second generation bioactive bonding of implants with tissues and no interfacial scar tissue. This chapter reviews the discovery that controlled release of biologically active Ca and Si ions from bioactive glasses leads to the up-regulation and activation of seven families of genes in osteoprogenitor cells that give rise to rapid bone regeneration. This finding offers the possibility of creating a new generation of gene activating bioceramics designed specially for tissue engineering and in situ regeneration of tissues.

Abstract: Septal cartilage is widely used for the repair of soft tissue defects in the head, neck and nose. Tissue Engineering techniques are being investigated to create cartilage in vitro by seeding appropriate cells on resorbable scaffolds. In this study, human chondrocytes were cultured on macroporous bioactive glass foam scaffolds. The aim was to investigate how Raman spectroscopy could be used as a non-invasive technique to monitor the response of chondrocytes to a 3D scaffold in real time. The spectra were compared to scanning electron microscope (SEM) micrographs and immunohistochemistry results.

Abstract: The Classical Least Square (CLS) fitting method was used to analyze the Raman spectra of living cells with the aim of identification of new phenotype-specific spectral markers for osteoblasts. The following chemicals were used for the CLS model: DNA, RNA, serum albumin, chymotrypsin and phosphatidyl choline. In this study we analyzed primary mature osteoblasts as well as two other cell types used as potential sources of osteoblasts: embryonic stem cells and fetal bone cells. The results obtained suggest that the Raman spectra of the cell types can be well approximated with a linear combination of the Raman spectra of the biopolymers used in the CLS model. The relative concentrations of the CLS components varied significantly between cell types, indicating that this analytical method could be used for phenotypic identification of osteoblasts.