1816-LB: Examining the Human Diabetic Bone Marrow Niche

Introduction & Objective: Patients with diabetes mellitus (DM) have a 30-fold increased risk of developing diabetes foot ulcers (DFUs), with 43% requiring lower extremity amputations (LEAs). While the underlying cause of non-healing DFUs is not known, abnormalities in bone marrow (BM)-derived immune cell dysfunction may play a key role. To study the effect of DM on human BM-derived innate immunity, we developed a human BM organoid system to directly study the human DM immune system from patients with DFUs.

Methods: BM was collected from a DM patient undergoing a LEA for treatment of a non-healing DFU. BM explants were cultured in a 3D protein matrix separately by two technicians. Resulting HSCs underwent in vitro differentiation into monocytes and macrophages. Human cord blood (HUCB)-derived HSCs cultured in a 3D protein matrix for expansion and characterized via FACS, a colony forming unit assay, and in vitro differentiation as a control.

Results: HUCB and BM derived HSCs were expanded in a 3D organoid culture. HSC pluripotency was tested by colony forming unit assay, FACS, and in vitro differentiation of HSCs to monocytes and macrophages. Monocytes and macrophages were produced in similar percentages and efficiencies before and after the 3D organoid culture. The in vitro differentiation of DM BM-derived HSCs yielded similar percentages of monocytes and macrophages and in similar efficiencies between technicians.

Conclusion: Our novel 3D organoid culture system successfully expands HSCs without altering HSC behavior. Expanded DM BM-derived HSCs are representative of inherent differences of the sample, as opposed to experimental handling. Therefore, this methodology can be used to directly understand the impact of DM on the human immune system and its role in DFUs.