Processing and CD3+/CD19+ depletion of cadaveric vertebral bone marrow for primary immunodeficiency patients undergoing sequential bilateral orthotopic lung transplant (BOLT) and bone marrow transplant (BMT)

Abstract

Background & Aim Patients with primary immune-deficiency (PID) may develop pulmonary complications and at that stage most are ineligible for either lung transplant (LTX) or bone marrow transplant (BMT) alone due to futility. We are conducting a first in human prospective trial, ClinicalTrials.gov: NCT01852370 where PID patients in lung failure -past the opportunity for curative BMT alone- may receive a 2 of 6 HLA antigen-matched cadaveric BOLT and minimum 8 weeks alter cryopreserved BMT from the same deceased UNOS donor. We hypothesized: 1) hematopoietic stem cells prepared from organ donor vertebral bodies (VB) would yield greater CD34+ cell dose compared to iliac crest aspirates-in part due to limited harvest time to avoid delay in the activity of organ recovery teams; 2) cryopreserved CD3/CD19 depleted bone marrow could generate durable hematopoiesis and donor derived immunity. Here we present the first 5 consecutive cases vertebral bone marrow (VBM) processing experience at Children's Hospital of Pittsburgh and subsequent CD3+/CD19+ cell depletion on the CliniMACS® device. With a threshold viability of 70% prior to cryopreservation the CD3/CD19-depleted product must contain 1 × 10E+6/kg CD34+ cells and 1 × 10E+5/kg CD3+ T cells to achieve durable engraftment and reduce the risk of GVHD respectively.® Methods, Results & Conclusion For details of pre/post processing, see Table. Since early 2017 we introduced chest/abdominal cavity wash with 1:1 saline-betadine mix and scrubbing T11-L4VB logs with chlora-prep that has eliminated bacterial contamination for the last 3 products. The first 2 were infused without adverse events following IRB/FDA approved antibiotic prophylaxis. Initially, processing of the VBs was arduous, using a scalpel and wire brush to clean the logs, then dissecting into small pieces with a mallet and osteotome. Since early 2017 a Stryker RemB saw has been used. A physical task that had taken 2 technologists 3 hours to complete has become almost effortless and one tech is freed up. The target pre-cryo CD34+ dose and viabilities have met target at all times, in fact CD34+ recovery has increased >70%, see Table. The entire process (dissection, crushing, filtering, CD3/CD19 depletion and cryopreservation) can be completed in 12 hours with 3 technologists. In summary, we have developed a complex sequence of procedures that even exceeded our target of 2E+06 CD34/kg pre-cryo dose (mean: 4.49E+06) leading to prompt and multilineage engraftment in 3 of the first 4 analyzable patients.