The goal of this study is to evaluate safety and efficacy of bone marrow (BM) as site for pancreatic islet transplantationin humans. Our hypothesis is that BM represents a better site than liver (currently the location of choice for this procedure) thanks to its potential capacity to favor islet engraftment. To address our hypothesis we propose herein a randomized phase II trial to compare BM and liver as sites for islet transplantation in T1D patients.

The study is a phase II, single center, open label, pilot study. We will recruit 12 patients with T1D to be randomly (1:1) assigned to receive islet either into the liver through the portal venous circulation (standard procedure; arm A, n=6) or directly into the BM at the level of the iliac crest (arm B, n=6). Patients will be selected from those eligible for islet Tx based on local practice and guidelines.

Inclusion Criteria:

• diabetic patients eligible for pancreatic islet transplantation based on local accepted practice and guidelines. This includes at least: a)clinical history compatible with T1D with insulin-dependence for >5 years; b) undetectable stimulated (arginine or MMTT) C-peptide levels (<0.3 ng/mL) in the 12 months before transplant c)presence of severe hypoglycaemic events

Exclusion Criteria:

• presence of hematologic disease