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Development of chimera recombinant collagenases G and H for the isolation of islets of Langerhans

Gregorio Seidita^1,2, Monica Salamone¹, Luca Lo Piccolo¹, Angela Cuttitta^1,3, Federico Bertuzzi^1,4, Antonello Pileggi⁵, R. Damaris Molano⁵, ElsIe Zahr-Akrawi⁵, Camillo Ricordi^1,5, Giulio Ghersi^1,6

¹ABIEL s.r.l., Palermo, Italy; ²Dipartimento di Biopatologia e Biotecnologie Mediche e Forensi, Università di Palermo, Palermo, Italy; ³Istituto per l’Ambiente Marino Costiero, CNR U.O.S. Capo Granitola, Campobello di Mazara (TP), Italy; ⁴Ospedale Niguarda Cà Granda, Milano, Italy; ⁵Diabetes Research Institute, University of Miami, Miami, FL, United States; ⁶Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Università di Palermo, Palermo, Italy

Since the 90’s, transplantation of allogeneic islets of Langerhans in patients with type 1 diabetes represent a successful example of human cell therapy. Nevertheless, islet isolation/purification procedure, at the moment, is not well standardized and a high percent (about 50%) of procedures don’t yield adequate islets for transplantation. This can be ascribed to several factors, including the variability in donor characteristics, pancreas recovery and preservation, as well as to unpredictable enzymatic blend efficiency. Currently, islets isolation from donor pancreas utilizes proteolytic enzymes obtained by extractive procedures from the Clostridium histolyticumbacteria. In particular, they contain collagenases (Class I and Class II) having degradation activity on several different collagen substrates, when compared to mammalian ones. However, some obstacles persist in human islet isolation success probably due to the variability in composition and concentration of collagenases used during the digestion phase.

To reduce the variability in collagenase composition in the blends usable for islets isolation, and to minimize the variability in enzyme composition, we have produced by DNA recombination protocols the major classes of C. histolyticum collagenases: collagenase G and collagenase H. We developed biosynthesis with high efficiency into specific clones of Escherichia coli of computationally optimized C. histolyticumcollagenases DNA sequences; which were inserted into inducible vectors together the maltose binding protein (MBP). The presence of MBP simplifies the purification process and stabilizes the obtained molecules. MBP-col G and MBP-col H chimeras were analyzed by the means of different approaches, to test their capability to digest artificial “in vitro” and natural “ex vivo” collagen substrates. By electrophoresis, zymography and spectrofluorimetric assays we have quantified and evaluated enzymatic activity of recombinant proteases. Recombinant collagenases efficiently dissociated mouse and rat pancreatic tissue to obtain free islets of Langerhans with well preserved morphological integrity, suggesting comparable activity to commercially available enzyme blends.