An attempt to induce tolerance with infusion of donor bone marrow in organ allograft recipients

Clinical implementation of a procedure to prepare bone marrow cells from cadaveric vertebral bodies

AIMS

Vertebral bone marrow is a rich and easily accessible source of hematopoietic and mesenchymal stem cells that has been used to promote chimerism and transplantation tolerance in connection with cadaveric organ transplantation. The purpose of this study is to provide a detailed account of the procedure used to prepare the first five vertebral bone marrow products for infusion in conjunction with the first hand/hand-forelimb transplants performed at the University of Pittsburgh (PA, USA).

MATERIALS & METHODS

The cell separation and release testing were performed at the University of Pittsburgh Cancer Institute's Hematopoietic Stem Cell Laboratory, a Good Manufacturing Practice-compliant facility accredited for clinical cell processing by the Foundation for Accreditation of Cellular Therapy (FACT) and for clinical flow cytometry by the College of American Pathologists (CAP).

Development and validation of a procedure to isolate viable bone marrow cells from the vertebrae of cadaveric organ donors for composite organ grafting

BACKGROUND AIMS

Donor-derived vertebral bone marrow (BM) has been proposed to promote chimerism in solid organ transplantation with cadaveric organs. Reports of successful weaning from immunosuppression in patients receiving directed donor transplants in combination with donor BM or blood cells and novel peri-transplant immunosuppression has renewed interest in implementing similar protocols with cadaveric organs.

METHODS

We performed six pre-clinical full-scale separations to adapt vertebral BM preparations to a good manufacturing practice (GMP) environment. Vertebral bodies L4-T8 were transported to a class 10 000 clean room, cleaned of soft tissue, divided and crushed in a prototype bone grinder. Bone fragments were irrigated with medium containing saline, albumin, DNAse and gentamicin, and strained through stainless steel sieves. Additional cells were eluted after two rounds of agitation using a prototype BM tumbler.

RESULTS

The majority of recovered cells (70.9 ± 14.1%, mean ± SD) were eluted directly from the crushed bone, whereas 22.3% and 5.9% were eluted after the first and second rounds of tumbling, respectively. Cells were pooled and filtered (500, 200 μm) using a BM collection kit. Larger lumbar vertebrae yielded about 1.6 times the cells of thoracic vertebrae. The average product yielded 5.2 ± 1.2 × 10(10) total cells, 6.2 ± 2.2 × 10(8) of which were CD45(+) CD34(+). Viability was 96.6 ± 1.9% and 99.1 ± 0.8%, respectively. Multicolor flow cytometry revealed distinct populations of CD34(+) CD90(+) CD117(dim) hematopoietic stem cells (15.5 ± 7.5% of the CD34 (+) cells) and CD45(-) CD73(+) CD105(+) mesenchymal stromal cells (0.04 ± 0.04% of the total cells).

CONCLUSIONS

This procedure can be used to prepare clinical-grade cells suitable for use in human allotransplantation in a GMP environment.