|
The materials used to fabricate scaffolds for tissue engineering are derived from synthetic
polymers, mainly from the polyester family, or from natural materials (e.g., collagen and chitosan). The
mechanical properties and the structural properties of these materials can be tailored by adjusting the
molecular weight, the crystalline state, and the ratio of monomers in the copolymers. Quality control and
adjustment of the scaffold manufacturing process are essential to achieve high standard scaffolds. Most
scaffolds are made from highly crystalline polymers, which inevitably result in their opaque appearance.
Their 3-D opaque structure prevents the observation of internal uneven surface structures of the scaffolds
under normal optical instruments, such as the traditional light microscope. The inability to easily monitor
the inner structure of scaffolds as well as the interface with the old bone poses a major challenge for
tissue engineering: it impedes the precise control and adjustment of the parameters that affect the cell
growth in response to various mimicked culture conditions.
The aim of this paper is to investigate the interface between the femur rat bone and the new bone
that is obtained using a method of tissue engineering that is based on different artificial matrixes inserted
in previously artificially induced defects. For this study, 15 rats were used in conformity with ethical
procedures. In all the femurs a round defect was induced by drilling with a 1 mm spherical Co-Cr surgical
drill. The matrixes used were Bioss and 4bone. These materials were inserted into the induced defects.
The femurs were investigated at 1 week, 1 month, 2 month and three month after the surgical procedures.
The interfaces were examined using Time Domain (TD) Optical Coherence Tomography (OCT)
combined with Confocal Microscopy (CM). The optical configuration uses two single mode directional
couplers with a superluminiscent diode as the source centered at 1300 nm. The scanning procedure is
similar to that used in any CM, where the fast scanning is en-face (line rate) and the scanning in depth is
much slower (at the frame rate).
The results showed open interfaces due to the insufficient healing process, as well as closed
interfaces due to a new bone formation inside the defect. The conclusion of this study is that TD-OCT can
act as a valuable tool in the investigation of the interface between the old bone and the one that has been
newly induced due to the osteoinductive process.
|
