Stem cells in personalizing implants
Mesenchymal stem cells (MSCs) are multipotent stromal stem cells that can be harvested from many different sources and differentiated into a variety of cell types. The effectiveness of MSCs based therapies is dependent on a gamut of factors which include differentiating state of the MSCs at the site of application, vehicle used and the nature/extent of injury. Tissue engineering and regenerative medicine, coupled with genetic engineering and gene therapy are revolutionizing the way cell therapy is performed these days. While several studies from different research groups have shown encouraging results wherein MSCs were used to develop personalized implants, the exact mechanism behind MSC mediated therapy is work in progress.
Scientists across the world are trying to answer the question of how stem cells aid in the repair process and what could be done to speed up the process of wound healing/repair. As is the case with many other novel therapies, stem cell based implants and their potential applications as an alternative to conventional implants with limited and inert efficacy is exploratory in nature. Despite the negative press about stem cell based therapies, scientists and clinicians across the world are reporting success stories wherein stem cells were able to replace or support the conventional treatment modalities, especially in the field of implantology. With the ever increasing demand for implants and enhancing wound healing procedures, stem cells could be playing a vital role in trying to meet these demands. With the current issue of Transcomm, our sincere effort is to educate the audience about the benefits of stem cells in implantology and to encourage stem cell storage as a very important short term investment that can have long term implications on their loved ones’ quality of life.
Implants and their limitations in application
A 36 year old male patient was detected with a primary tumor in his distal trachea and main bronchi, recurrent and cancerous and of inoperable size. He was previously treated with debulking surgery and radiation therapy, but constant recurrence of the cancerous tissue forced the doctors to adopt a cell based therapy. After the tumour was resected, the airway was substituted with a tailored bioartificial nanocomposite containing autologous bone-marrow mononuclear cells. 5 months post transplantation, the patient is tumour free and asymptomatic. Postoperatively, mobilization of peripheral mesenchymal stromal cells was detected, along with up-regulation of receptors, non- apoptotic genes and regeneration-associated plasma factors which showed the signs of ECM remodeling, cell mediated wound healing, neovascularisation of the graft. This study confirmed the potential of tailor made bioartificial scaffolds with cells to replace complex airway defects.
In a sinus augmentation procedure, the optimal bone formation takes approximately 6-9 months post-surgery, despite using standard grafting materials along with an autogenous bone graft. Therefore for a faster recovery process and bone formation, sinus-augmentation procedure was conducted with an allograft cellular bone matrix (ACBM), containing native mesenchymal stem cells and osteoprogenitors. Post-surgery, there was an improvement in the amount of vital bone content along with an increase in the average healing period which was now within the range of about 3.7-4 months. The high percentage of vital bone content, along with the relatively short healing phase, emphasize the importance of usage of stem cells for implant placement and restoration when considering a cellular implant method.
A 48-year old patient presented with a partial edentulous lower jaw wished for a surgical intervention or implant supported fix for the situation. A stem cell based subepithelial connective tissue graft along with allogenic human bone segments was used in his. The sterile allograft bone product/block which carried the stem cells was derived from human donor bone, which had very high regenerative and osteoconductive properties. These bone blocks were attached to a spongy bone base and were held in place by osteosynthesis screws using a 3D copying machine. Subepithelial connective tissue graft (SCTG), the source of mesenchymal stem cells has been derived from the region between 2nd premolar – 2nd molar. The SCTG graft successfully got incorporated into the recipient site.
Stem cell therapy can play a pivotal role in the treatment of craniofacial bone defects. In a study stem cells and progenitor cells were isolated from the bone marrow, also known as tissue repair cells. 24 patients who required facial/jawbone reconstruction procedures participated in this trial .The patients received stem cell based therapy along with oral implants functionally loaded with tooth restorations along with the control group which received guided bone regeneration (GBR). The patients of both the groups were observed 1 year post therapy. While not showing any adverse effects, stem cell therapy assisted in accelerated alveolar bone regeneration, thereby reducing the need for secondary bone graft.
In a study involving four patients with large bone diaphysis defects, a novel tissue engineering approach was used where in stem cells were isolated from the patient’s bone marrow and cultured to get the desired numbers and then seeded onto porous hydroxyapatite (HA) ceramic scaffolds. This scaffold was drawn to match individual patients bone deficit in terms of size and shape. During surgery, the 3D construct-ceramic scaffolds containing the cells were placed in the area containing the bone defect. The patients who took part in this study were closely monitored for a year post surgery and showed no signs of infections or complications. The last follow up was done 6 to 7 years post-surgery with no complications and the implants remained integrated with no fractures, proving the long term reliability of stem cell therapy.