JOINT BASE SAN ANTONIO-FORT SAM HOUSTON, Texas —
A research project being conducted at Naval Medical Research Unit San Antonio, or NAMRU-SA, at Joint Base San Antonio-Fort Sam Houston, could lead to a better method for bone regeneration and improve treatment for service members and patients whose bone tissue has been damaged by a traumatic injury.
The project, which started in 2015, is incorporating the use and researching the effectiveness of biological therapeutics, including stromal cells, in promoting bone regeneration and growth in damaged bone tissue.
Dr. Alexander Burdette, NAMRU-SA principal investigator, said the objective of the research project is to find out if biological therapeutics can provide a better and effective way of healing critical size bone defects – a bone defect size that is too large to heal on its own – than the current treatment of bone grafting, living bone tissue that is transplanted from one part of the body to the defect site located at another part of the body.
Burdette said bone grafting can heal damaged bone tissue over time, but it has several disadvantages for the patient, particularly a service member with a traumatic injury. Bone grafting requires multiple surgeries, is dependent on the limited availability of bone that can be used as graft, can result in donor site morbidity and prolongs in-patient care, which can lead to higher healthcare costs.
“Someone who is exposed to an IED (improvised explosive device) blast can have a lot of trauma on them,” Burdette said. “The last thing they need to experience is another surgery to harvest the bone to do grafting on them.”
To come up with other options for treating damaged bone tissue, NAMRU-SA researchers utilized a biological therapeutic from amnion-derived multipotent progenitor, or AMP, cells known as secretome. The secretome contained secreted proteins that are vital to the process of bone regeneration and bone growth.
Researchers placed the secretome in a collagen scaffold. A collagen scaffold contains the main structural protein found in various connective tissues in the body, including tendons, ligaments and skin. The scaffold serves as a framework or structural element that allows cellular infiltration to the defect site with cell adhesion to the scaffold, followed by proliferation and osteogenic differentiation.
Burdette said the scaffold with the secretome is put in the bone defect area and includes growth factors that attract and enhance the growth of mesenchymal stromal cells, which are cells that differentiate into a variety of cell types, as well as osteoprogenitor cells, which are found in the bone marrow and work in the growth or repair of bones.
Once they are in the scaffold, the cells get signals from host cells surrounding the bone defect area to begin proliferating and differentiating, starting bone regeneration and producing new bone tissue.
Research done in in vitro pre-clinical studies show that the secretome biological therapeutic improved the proliferation and migration of mesenchymal stromal cells, Burdette said. In addition, utilizing the collagen scaffold with the secretome in vivo increased bone volume and improved quality and connectivity and healed the bone at a quicker rate in a span from one to three months.