Laminin 411 acts as a potent inducer of umbilical cord mesenchymal stem cell differentiation into insulin-producing cells

Qu H., Liu X., Ni Y., Jiang Y., Feng X., Xiao J., Guo Y., Kong D., Li A., Li X., Zhuang X., Wang Z., Wang Y., Chang Y., Chen S., Kong F., Zhang X., Zhao S., Sun Y., Xu D., Wang D., Zheng C.
Journal of Translational Medicine, 2014

Efficient induction of differentiation to insulin-producing cells from MSCs. Up-regulated insulin expression at both mRNA and protein levels. Administration of the insulin producing cells in T1 diabetes rats rapidly 1) down-regulated fasting blood glucose levels, 2) significantly reduced the HbA1c concentration and 3) markedly improved the symptoms and survival of the rats.

 

The Vascular Basement Membrane: A Niche for Insulin Gene Expression and B Cell Proliferation

Nikolova G., Jabs N., Konstantinova I., Domogatskaya A., Tryggvason K., Sorokin L., Fässler R., Gu G., Gerber H-P., Ferrara N., Melton D.A., Lammert E.
Developmental Cell, 2006

Mouse pancreatic islets intimately interact with endothelial cells and differentiation and delamination of insulin-producing b cells from pancreatic epithelium strictly require endothelial cells. Doug Melton and colleagues show that BMs within islets is formed and found exclusively around capillaries but not islet cells. Islet endothelial cells express laminin a4 and a5. Laminins promote insulin gene expression and proliferation in B-cells and B1-intergrin is required for this laminin response. Laminin-411 and -511 worked well but also laminin-111 which shows that the applied laminin does not necessarily have to be endothelial cell-derived. Research on islet transplantation has shown that it takes about 1–2 weeks for transplanted islets to become revascularized in the host and the authors suggest that treating islets with these laminins prior to transplantation will help maintain insulin production until new capillaries are formed in transplanted islets.

 

Co-culture with extracellular matrix proteins reduces hypoxia-induced human islet cell death

Brandhorst et al., Xenotransplantation, Abstracts of the IPITA-IXA-CTS 2015 Joint Congress November 15–19, 2015, Melbourne, Australia

Islets are experiencing hypoxic conditions after transplantation. The aim of this study was to assess the effect of collagen IV and laminin isoform -521, -511 and -411 on survival and function of isolated human islets exposed to severe hypoxia. Compared with hypoxic controls (100%) all ECMs significantly increased islet recovery after culture at 0.75% oxygen ranging from 163 +/- 12% to 173 +/- 28% (P < 0.05) using collagen IV or laminin-411, respectively. Increased post-culture recovery correlated with decreased islet fragmentation which was lowest using laminin-521 (66%, P < 0.01) and laminin-511 (66% P < 0.05). Islet ROS generation was also lowest after culture with laminin-521 and laminin-511. Islet viability was increased in all experimental groups when compared to controls but was highest using collagen IV and laminin-511. This observation corresponds to the insulin response after glucose challenge that was best preserved when collagen IV or laminin-511 were used for islet incubation.

 

Human Laminin Isotype Coating for Creating Islet Cell Sheets

Yamashita S., Ohashi K., Utoh R., Okano T., Yamamoto M.
Cell Medicine, 2015

This study describe an experimental approach to create a monolayered islet cell construct (islet cell sheet), followed by transplantation into a subcutaneous pocket. The authors try to identify an optimal human ECM as a coating material on PIPAAm surfaces, which allowed rat islet cells to attach on the surfaces and subsequently to be harvested as a monolithic cell sheet. Dispersed rat islet cells were seeded onto PIPAAm dishes coated with various human laminin isotypes: LN211, LN332, LN411, LN511, and HL-placenta. The highest value of plating efficiency was found in the HL-332-PIPAAm group (83.1 ± 0.7%). The HL-332-PIPAAm group also showed the highest cellular confluency (98.6 ± 0.5%). Islet cells cultured on the HL-332-PIPAAm surfaces showed a positive response in the glucose-stimulated insulin secretion test. LN511 also showed good results.

 

Unique basement membrane structure of human pancreatic islets: implications for b-cell growth and differentiation

Otonkoski T., Banerjee M., Korsgren O., Thornell L.-E., Virtanen I.
Diabetes, Obesity and Metabolism, 2008

The authors shown that in the human islets, a double BM structure surrounding each blood vessel within the islet. In addition, a continuous peri-islet BM was surrounding the entire islet, invaginating into the islet tissue together with the arterioles. The capillaries are surrounded by a double BM both in foetal and adult tissues. The B-cells are facing a BM that is separate from the endothelia, unlike the situation in mouse where the B-cells interact directly with BMs of capillary endothelial cells. Here they show that (i) a1 is not expressed in the adult human pancreas; (ii) a2 is only expressed in the exocrine pancreas; (iii) a4 is expressed in the blood vessel BMs; (iv) a5 and b1 are expressed similarly, both in the endocrine and endothelial BMs in the islets. Taken together, this suggested that there is a double-layered BM organization around the vascular channels of human islets: the inner vascular leaflet of the duplex contains Lms-411/421 and -511/521 whereas the outer leaflet facing the parenchymal endocrine cells contains only Lm-511. In contrast to the adult pancreas, laminin a1 chain could be found in the acinar BMs of fetal pancreas and faintly also in the developing islets. Similarly, as in the adult pancreas, immunoreactivity for laminin a5 chain was distinctly surrounding the developing islets and also in BMs of intra-islet vessels. Strong expression of laminin B1 and g1 in fetal pancreas.  a3 and b1 integrin subunits were found both on the vascular channels and the endocrine cells. However, integrin a6 subunit was clearly absent from the endocrine cells and only expressed in the endothelial cells. The islet cells facing this BM have a strong and polarized expression of Lutheran glycoprotein, which is a well-known receptor for the laminin a5 chain. Dispersed human islet cells adhere to purified human laminin-511 and the binding is equally effectively blocked by a soluble form of Lutheran as by antibody against integrin B1. The results reveal that the BM structure of human islets, different from rodents.

 

Key matrix proteins within the pancreatic islet basement membrane are differentially digested during human islet isolation

Cross S.E., Vaughan R.H., Willcox A.J., McBride A.J., Abraham A.A., Han B., Johnson J.D., Maillard E., Bateman P.A., Ramracheya R.D., Rorsman P., Kadler K.E., Dunne M.J., Hughes S.J., Johnson P.R.V.
Am J Transplant. 2016

Here the authors investigated the impact of islet isolation on basement membrane (BM) integrity in human islet. Collagen IV, panlaminin, perlecan and laminin-α5 in the islet BM were significantly digested by enzyme treatment. Laminin-α5 (found in both layers of the duplex BM) and perlecan were lost entirely, with no restoration evident during culture. Islet function and survival decreased and islet cytotoxicity increased during culture. The islet basement membrane (BM) influences islet function and survival and an incomplete islet BM has implications for islet integrity and transplanted graft longevity.

 

Extracellular matrix microarrays to study inductive signaling for endoderm specification

Braga Malta D.F., Reticker-Flynn N.E., da Silva C.L.,. Cabral J.M.S, Fleming H.E., Zaret K.S., Bhatia S.N., Underhill G.H.
Acta Biomaterialia, 2016

The authors implemented an extracellular matrix (ECM) array platform that facilitates the study of 741 distinct combinations of 38 different ECM components in a systematic, unbiased and high throughput manner. Seeded definitive endoderm (DE) cells onto the arrays and evaluated cell adhesion and hepatic and pancreatic differentiation. When comparing the ECM conditions that best supported hepatic and pancreatic differentiation, we noted that two combinations (fibronectin + merosin (laminin α2) and laminin (α1) + superfibronectin) are among the most robust domains for both hepatic and pancreatic differentiation.