Direct Intra-Bone Cord-Blood Transplantation Overcomes the Problem of Graft Failure Even When Low Numbers of HLA-Mismatched Cord- Blood Cells Are Transplanted, Thus Leading to the Possibility of Use of This Technique in a Large Number of Patients.

Cord blood transplant (CBT) is associated with delayed or failed engraftment in about 20% of patients. We present here the results of intra-bone (IB) transplant of cord blood cells from two Institutions. Fifty-eight consecutive adult patients were included in this study. Patients were: 29 AMLs (10 in first, 3 in second remission and 15 in advanced stage,1 secondary), 15 ALLs (1 in first, 5 in second remission and 9 in advanced stage) 4 CMLs (2 Acc. Phase, 2 Blastic Transformation), 3 refractory Hodgking Disease, 4 refractory Non-Hodgking Lymphomas (HD), 1 Atypical myeloproliferative disease (after HD), 1 SAA and 1 Diskeratosis Congenita (DC). Patients’ median age was 36 years (18–66). Human Leukocyte Antigen (HLA) matching was 6/6, 5/6, 4/6 and 3/6 for one, 10, 46 and one patient, respectively. Conditionig Regimen consisted in: fractionated TBI (10–12 Gy)/cyclophosphamide(CTX) (n=42), Fludarabin (Flu)-CTX-TBI 2 Gy (n=6), Treosulfan (Treo)-Thiotepa (TT)-Flu (n=10). Median transplanted cell dose was 2.6 x10⁷/kg (1.4–5.4) and CD34+ cell dose was 0.83 x10⁵/kg (0.42–4.53). Cord blood cells were gently infused in the supero-posterior iliac crest (SPIC) under rapid general anaesthesia. In 21 patients the procedure was performed in both (right and left) SPIC while in 37 patients in either left or right SPIC. No complications were observed during or after the IB infusion of cells. Eight patients with advanced disease died within 12 days from transplant. Two patients did not engraft; one (SAA) had a second IB CBT but engrafted only after mesenchymal stem cell infusion; the other patient (CML-AP) is being re-transplanted. All other patients engrafted. Median time to neutrophils (PMN) and platelet (Plt) recovery was day +23 (14–44) and day +38 (16–64) respectively. Kaplan-Meier probabilities were then 100% for both PMN and Plt. at day +44 and day +64, respectively. Cumulative incidence were 87% (95% CI: 73–97) at day +44 for PMN and 82% (95% CI: 67–95) at day +64 for Plt. At day +30 haematopoietic progenitors Colony Forming Cells frequency were within the limit of normal range both in injected and un-injected site; this shows a rapid recirculation and seeding in the entire hematopoietic system. Chimerism was 100 % donor in all patients from day +60. In 47 patients at risk for acute Graft-versus-Host Disease (GVHD) the score was: grade 0 (n=37) grade I (n=3) and grade II (n=6), grade III (n=1). Seven patients had moderate and two patients extensive chronic GVHD. Causes of death were multiorgan failure(n=8), infections (n=12), PTLD (n=1) and relapse/progression (n=5). Thirty-two patients are alive: 4 in relapse/progression; one with graft failure; and 27 in haematological remission at a median follow-up of 20 months (2–29). Three pediatric patients (age 1– 7 years) were also included in this study: 1 JMML in graft failure after BMT; 1 ALL with t (9;22) in first CR and 1 Hemophagocytic Lymphohistiocytosis (HLH) with active disease following three unrelated BMT. HLA matching was 5/6 (1pt) and 4/6 (2 pts); Conditioning Regimen were: TT+Flu+L-PAM, TBI 12 Gy +CTX+TT, Treo+TT+Flu; median cell dose injected IB was 4.6 x10⁷ TNC (3.0–7.0) and 0.76 x10⁵ CD34+ (0.3–2) respectively. Patients achieved PMN and Plt. recovery at 12-27-47 and 31-34-63 days from IB-injection. All patients are alive, disease-free and full donor chimerism at 249, 172 and 85 days following IB CBT. Our data suggest that direct i.b. cord blood transplant is associated with a very high rate of engraftment even when low numbers of HLA mismatched cord blood cells are transplanted, thus, rendering this transplant possible in a greater number of patients with hematologic diseases. Moreover, high risk pediatric patients may also benefit of IB transplant as salvage procedure.