Individual bone grafts are created from stem cells

Scientists from New York Stem Cell Foundation (NYSCF) Research Institute have developed a new method of bone tissue repair called Segmental Additive Tissue Engineering (SATE).

The technique, described in the article, which was published in Scientific Reports, allows researchers to combine bone segments grown from stem cells to create personalized transplants that improve the treatment of patients suffering from bone diseases or injuries.

“We are hopeful that SATE will one day be able to improve the lives of the millions of people suffering from bone injury due to trauma, cancer, osteoporosis, osteonecrosis, and other devastating conditions”, – says Susan L. Solomon, NYSCF CEO. “Our goal is to help these patients return to normal life, and by leveraging the power of regenerative medicine, SATE brings us one step closer to reaching that goal.”

More than a million people will suffer from problem of fractures caused by bone diseases every year. In addition, with aging, the bones become weak, leading to various complications later in life. Injuries resulting from road traffic accidents or violence, as well as congenital diseases such as, for example, imperfect osteogenesis, require more and more donor bone tissue, the deficit of which becomes ever more tangible.

“Bone defects obtained in disease or injury are a growing issue, and having effective treatment options in place for personalized relief, no matter the severity of a patient’s condition, is of critical importance”, – explains Giuseppe de Peppo, PhD, who led the study.

Currently, bone defects are corrected either by synthetic substitutes or bone grafts obtained from the healthy bones of the patient himself or from the bone tissue bank. However, these methods of treatment often cause immune rejection, do not lead to the formation of connective tissue or vascular system, necessary for the functional bone.

In addition, such transplants should often be replaced in children who “outgrow” them. Bone grafts created from the patient’s stem cells lack similar side effects, but their size and shape for extensive injuries are difficult to design with high accuracy.

“As the size of the defect that needs to be replaced gets larger, it becomes harder to reproducibly create a graft that can move from the lab to the clinic”, – says NYSCF researcher Dr. Martina Sladkova, the study’s first author.

“We wanted to see if we could instead engineer smaller segments of bone individually and then combine them to create a graft that overcomes the current limitations in the size and shape of a bone that can be grown in the lab.”

To solve this issue, the team developed a transplant corresponding to a rabbit hip defect that affected about 30% of the total bone volume. To estimate the size and shape of the defect, scientists scanned the femur and created a model of the graft. Then they divided the model into smaller segments and created customized scaffolds for each.

The researchers then placed these scaffolds, fitted with mesodermal progenitor cells derived from iPSCs (induced human pluripotent stem cells) into a bioreactor specifically designed for bone grafts with a wide range of sizes. This bioreactor was able to ensure the uniform development of tissue throughout the transplant, which is often beyond the power of existing versions of similar devices used.

After the growth and filling of the framework with cells, the bone graft segments can be combined with adhesives or other orthopedic devices into a single mechanically stable graft.

SATE is standardized, versatile and easy to use. Its use will accelerate the transfer of bioengineering bone grafts from the laboratory to the clinic. The researchers are confident in the potential of SATE, which will help improve the quality of life of children and adults suffering from segmental bone defects.