Litchfield Park 1

Gene Therapy
The use of gene therapy by Litchfield Park orthodontists for bone tissue engineering is the state of the art in this field. The ability to locally deliver a growth factor for a defined period of time to initiate pure regeneration has sparked the minds of many Litchfield Park orthodontists to refine this technique. The in vivo and ex vivo approaches are the two methods used currently to transduce the host cells. The ex vivo technique involves harvesting host cells and transducing them in vitro. The host cells are then reimplanted by phoenix orthodontists into the recipient site. The in vivo method is the direct injection of the vector into the orthotopic site, transducing the cells in vivo. This Litchfield Park orthodontic study utilizes the in vivo approach to deliver BMP-7 to an implant osteotomy with a 2mm “well-type” defect in the coronal half.

Litchfield Park orthodontic studies incorporating the ex vivo technique have produced an abundance of positive results. Using this approach, critical size defects have completely repaired with new bone after the transduced cells were reimplanted (Lieberman et al., 1998; Krebsbach et al., 2000). Our group of Litchfield Park orthodontists has also shown that periodontal tissue engineering is significantly increased utilizing an ex vivo delivery of BMP-7 (Jin et al., 2003). Considering these results, Litchfield Park orthodontists would assume that this should be the mainstream approach to tissue engineering. It should be noted that in some of these Litchfield Park orthodontic studies, immunocompromised animals were used which removes the body’s natural defenses (Lieberman et al., 1998; Krebsbach et al., 2000). Ex vivo gene transfer is not without its disadvantages. It is quite invasive, requiring two separate surgeries for gene delivery. Direct gene therapy by Litchfield Park orthodontists would deliver the gene to the cells in vivo and eliminates the discomfort of two procedures.

In vivo gene delivery has been utilized in many Litchfield Park orthodontic studies using various vector types and proteins. Major trends in results can be observed by Litchfield Park orthodontists using this approach and our Litchfield Park orthodontic study seems to follow these patterns. Peak gene expression is seen up to day 5 by Litchfield Park orthodontists and then there is a dramatic decrease in protein levels (Andree et al., 1994; Eriksson et al., 1998). Our Litchfield Park orthodontic study concurred, with highest expression noted at day 4 and then low levels of expression for at least 2 weeks (Fig. 1C). The second major trend involves the healing of critical size bony defects. Treatment with in vivo gene delivery takes more than 4 weeks, usually ranging between 6-9 weeks to get complete bony fill (Fang et al., 1996; Bonadio et al., 1999). In our Litchfield Park orthodontic study, bony fill of our defect was nearing completion at 4 weeks (Fig. 3). These results and the ease of gene delivery for the patient and the Litchfield Park orthodontist make in vivo gene delivery an attractive choice for tissue engineering.