Abstract
Introduction
Due to their properties and characteristics, human mesenchymal stem cells (MSCs) appear to have great therapeutic potential, because they can contribute to the tissue regeneration. Many different populations of MSCs that differ for the embryonic origin and the anatomical localization have been described and to understand whether they have equivalent biological properties is a critical issue for their therapeutic application. Spine fusion is frequently used to treat traumatic, degenerative, and oncological spine diseases. Autologous bone graft has been considered the gold standard for spine fusion procedures because of its osteogenic, osteoinductive, and osteoconductive ability. However, its use is associated with significant disadvantages, including donor site pain, increased operative time, insufficient availability, and nonunion postlumbar fusion. Various bone substitutes have been developed to promote spinal fusion. Also, MSCs have been successfully tested for spinal fusion in several small and large animal models.
Material and Methods
To define the properties of MSCs for the use in clinical applications, we proposed to analyze the cellular and molecular characteristics of human adult MSCs derived from different body locations, such as bone marrow from the iliac crest (Ic-MSCs), sternum (St-MSCs), and vertebrae (vMSCs), as well as colon (Co-MSCs) and dental pulp (DPSCs), to identify the cell population showing better biological properties for spine fusion clinical application.
Results
MSCs from different sources presented very different growth kinetics. While iliac crest and sternum-derived MSCs could be maintained in culture for about 3 months, undergoing a limited expansion, mesenchymal cultures derived from dental pulp and colon grew much more rapidly, but could not be maintained longer. Strikingly, vMSCs continued to propagate at high rate even after 3.5 months ex vivo. MSCs from different sources were also induced to osteogenic, adipogenic, and chondrogenic differentiation following exposure to specific inducing agents. We observed that vMSCs generate mature cells of all mesenchymal lineages with greater efficiency, resulting into the best population both in terms of expansion and differentiation.
Conclusion
This finding could be very interesting and open new perspectives for the improvement of spine fusion, which is a mandatory step for the success of spinal surgical procedures. In the course of a surgical procedure for spinal fusion, vertebral bone marrow can be harvested simultaneously with the preparation of the site for pedicle screw insertion. Then multipotent MSCs can be isolated from vertebral bone marrow during the progress of the surgical procedure and reintroduced in the fusion site (using homologous or autologous bone tissue or biomaterials as scaffold), without any additional surgical time or any other donor site involvement.