Autologous pancreatic islet transplantation in human bone marrow

Abstract

The liver is the current site of choice for pancreatic islet transplantation, even though it is far from being ideal. We recently have shown in mice that the bone marrow (BM) may be a valid alternative to the liver, and here we report a pilot study to test feasibility and safety of BM as a site for islet transplantation in humans. Four patients who developed diabetes after total pancreatectomy were candidates for the autologous transplantation of pancreatic islet. Because the patients had contraindications for intraportal infusion, islets were infused in the BM. In all recipients, islets engrafted successfully as shown by measurable posttransplantation C-peptide levels and histopathological evidence of insulin-producing cells or molecular markers of endocrine tissue in BM biopsy samples analyzed during follow-up. Thus far, we have recorded no adverse events related to the infusion procedure or the presence of islets in the BM. Islet function was sustained for the maximum follow-up of 944 days. The encouraging results of this pilot study provide new perspectives in identifying alternative sites for islet infusion in patients with type 1 diabetes. Moreover, this is the first unequivocal example of successful engraftment of endocrine tissue in the BM in humans.

FIG. 1.

Metabolic control and graft function after IAT. Insulin requirement and fasting C-peptide after IAT. Data are shown for each individual patient. Left axis: Exogenous insulin requirement expressed as IU/kg/day. Right axis: Fasting C-peptide expressed as ng/mL. The gray area represents the adjuvant therapy treatment for primary cancer during follow-up (chemotherapy or radiotherapy or both). Dotted line represents median fasting C-peptide (interquartile range represented by the yellow area) of 13 consecutive patients with total pancreatectomy receiving intraportal autologous islet infusion (median, 1,939 IEQ/kg; 25–75th percentiles, 1,659–2,151 IEQ/kg; min-max, 628–3,154 IEQ/kg) at our center during the same period. □, insulin requirement; ●, C-peptide.

FIG. 2.

BM morphology at day 4 posttransplantation. Photomicrographs of BM tissue obtained from the postmortem examination of patient 1. A: Histological appearance (left panel, magnification 100×; right panel, inset of left panel, magnification 400×) of transplanted tissue. Hematoxylin and eosin staining. Str, stromal reaction; Is, pancreatic islet; Epit, epithelial pancreatic cells. B: Representative immunohistochemical stainings (magnification 200×) with anti-insulin, antiglucagon, anticytokeratin 8–18 (cytokeratin 8–18), and anti-CD34 antibodies.

FIG. 3.

BM morphology at 1 year posttransplantation. Photomicrographs of BM biopsy samples from patient 3. A: Histological appearance (left panel, magnification 200×; right panel, inset of left panel, magnification 400×) of transplanted tissue. Hematoxylin and eosin staining. B: Representative immunohistochemical stainings (magnification 200×) with anti-insulin, antiglucagon, antichromogranin A, antisomatostatin, antipancreatic polypeptide, and anti-CD34 antibodies.

FIG. 4.

BM biopsy molecular assay. Scatter plot comparing the normalized expression (2^−ΔCt) of every gene with graft-bearing and contralateral BM. The central line indicates unchanged gene expression and the dashed line indicates the boundary (fold regulation cutoff set = 3). Expression changes greater than the selected boundary (filled circles) and expression changes smaller than the selected boundary (gray circles) are shown.

FIG. 5.

MRI and computed tomography scan of iliac BM. MRI T2-weighted images acquired 30 and 90 days and 1 year after islet transplantation in patient 3 (left). A small hypointense area (red circle) inside the normal hyperintense signal was evident at the site of the islet infusion at the level of the posterior-superior iliac spine. The gadolinium-enhanced MR perfusion study did not show areas of anomalous enhancement surrounding the site of the islets infusion (right). A computed tomography scan showed the presence of a small calcified spot at the site of islet infusion (lower right).