- Bone marrow transplant is a common procedure to treat marrow diseases such as aplastic anemia or immune destruction of the marrow.
- Pre-treatment of patient’s marrow by radiation before a transplant is associated with undesirable side effects.
- New lab designed bone marrow can be implanted beneath skin thus eliminating need for host marrow irradiation.
Accessory bone designed by bioengineering professor Shyni Varghese and her team at the UC San Diego Jacobs School of Engineering can be implanted under the skin where they have their unique space to grow without competition from host marrow cells, eliminating the need for the latter cells to be wiped out unnecessary.
Aim of the Research
The aim of this research was to make bone marrow transplant safe and free from unwanted side effects for the patient.
Usually, the patient's marrow is pre-treated with irradiation prior to a marrow transplant to destroy host cells and create space for donor cells to grow. The pre-treatment is done to improve the chances of success of bone marrow transplant but is associated with undesirable side effects such as fatigue, nausea, vomiting, and infertility.
Details And Results of the Current Research
- The research team developed an accessory bone similar to normal long bones in the body with an outer porous hydrogel matrix composed of calcium phosphate minerals and an inner marrow cavity.
- The engineered bone was filled with donor stem cells and implanted beneath the skin of mice.
- Stem cells in the outer matrix developed into mature bone cells with a vascular network. The inner marrow which held the donor stem cells grew and differentiated into blood cells in the host.
- Four weeks after the implant, the team found that the implanted marrow contained a mixture of donor and host cells confirming that donor stem cells and host cells traveled between the host bloodstream and the implanted marrow via the vascular network in the bony matrix.
- The same mixture of donor and host cells was found circulating in the bloodstream even 24 weeks after the procedure.
- The team of scientists also took stem cells form the implanted marrow and infused them into mice whose marrow had been destroyed by drugs or radiation.
- It was noted that the transplanted stem cells also reached the bloodstream of the host.
Scope of the Research
If further studies establish the safety and efficacy of engineered bone marrow implants, it could lead to safer and effective therapy for various bone marrow diseases. "In the future, our work could contribute to improved therapies for bone marrow disease," said Shih.
However, bone marrow implants can only be used in non-cancerous lesions of the marrow, since in case of malignancy, pre-treatment radiation of marrow is essential to wipe out the cancer cells before a bone marrow transplant can be done. Varghese reiterates this and cautions that these implants would be limited to patients with non-malignant bone marrow diseases, where there are no cancerous cells that need to be eliminated.
Future Research Plans
The research team is using this model to produce more bone marrow stem cells that may find applications in cell transplantations in the future.