Platelets generated from human embryonic stem cells are functional in vitro and in the microcirculation of living mice

Platelets play an essential role in hemostasis and atherothrombosis. Owing to their short storage time, there is constant demand for this life-saving blood component. In this study, we report that it is feasible to generate functional megakaryocytes and platelets from human embryonic stem cells (hESCs) on a large scale. Differential-interference contrast and electron microscopy analyses showed that ultrastructural and morphological features of hESC-derived platelets were indistinguishable from those of normal blood platelets. In functional assays, hESC-derived platelets responded to thrombin stimulation, formed microaggregates, and facilitated clot formation/retraction in vitro. Live cell microscopy demonstrated that hESC-platelets formed lamellipodia and filopodia in response to thrombin activation, and tethered to each other as observed in normal blood. Using real-time intravital imaging with high-speed video microscopy, we have also shown that hESC-derived platelets contribute to developing thrombi at sites of laser-induced vascular injury in mice, providing the first evidence for in vivo functionality of hESC-derived platelets. These results represent an important step toward generating an unlimited supply of platelets for transfusion. Since platelets contain no genetic material, they are ideal candidates for early clinical translation involving human pluripotent stem cells

Efficacy of the Oxygen-Charged Static Two-Layer Method for Short-Term Pancreas Preservation and Islet Isolation From Nonhuman Primate and Human Pancreata

Previous reports indicate that the two-layer method (TLM) of human pancreas preservation is superior to University of Wisconsin solution (UW) when pancreata are preserved for extended periods (i.e., \u3e24 h) prior to islet isolation. In this study, the efficacy of using the TLM for preserving pancreata for short periods (i.e., \u3c13 h) was evaluated using both nonhuman primate and human pancreata preserved with a TLM kit precharged with oxygen. An oxygen precharged TLM (static TLM) was established and compared with the original TLM with continuous oxygen supply. For the static TLM, the perfluorochemical was fully oxygenated and the oxygen supply removed prior to pancreas preservation. In the primate model, pancreata were preserved by the static TLM, the original TLM, and UW for 5 h prior to islet isolation. In the human model, pancreata were preserved with the static TLM or the original TLM or UW for 4–13 h. Both primate and human pancreata were processed by intraductal collagenase injection and digestion followed by continuous density gradient purification to isolate islets. Islets were assessed for islet yield, purity, viability, and in vitro functionality. In the primate model, islet yield, viability, and in vitro functionality were significantly improved by both the static TLM and the original TLM with similar results. Postculture islet yields were 23,877 ± 3619 IE/g in the static TLM, 21,895 ± 3742 IE/g in the original TLM, and 6773 ± 735 IE/g in UW. In the human model, both the static TLM and the original TLM significantly increased islet yield compared with UW with postculture islet yields of 2659 ± 549 IE/g in the static TLM, 2244 ± 557 IE/g in the original TLM, and 1293 ± 451 IE/g in UW. Nonhuman primate and human pancreata stored in the static TLM, immediately upon procurement, yield isolated islets of a substantially higher quantity than when pancreata are stored in UW. Thus, the use of the static TLM should replace the use of UW for storage of pancreata during transport prior to islet isolation

Efficacy of the Oxygen-Charged Static Two-Layer Method for Short-Term Pancreas Preservation and Islet Isolation From Nonhuman Primate and Human Pancreata

Previous reports indicate that the two-layer method (TLM) of human pancreas preservation is superior to University of Wisconsin solution (UW) when pancreata are preserved for extended periods (i.e., \u3e24 h) prior to islet isolation. In this study, the efficacy of using the TLM for preserving pancreata for short periods (i.e., \u3c13 h) was evaluated using both nonhuman primate and human pancreata preserved with a TLM kit precharged with oxygen. An oxygen precharged TLM (static TLM) was established and compared with the original TLM with continuous oxygen supply. For the static TLM, the perfluorochemical was fully oxygenated and the oxygen supply removed prior to pancreas preservation. In the primate model, pancreata were preserved by the static TLM, the original TLM, and UW for 5 h prior to islet isolation. In the human model, pancreata were preserved with the static TLM or the original TLM or UW for 4–13 h. Both primate and human pancreata were processed by intraductal collagenase injection and digestion followed by continuous density gradient purification to isolate islets. Islets were assessed for islet yield, purity, viability, and in vitro functionality. In the primate model, islet yield, viability, and in vitro functionality were significantly improved by both the static TLM and the original TLM with similar results. Postculture islet yields were 23,877 ± 3619 IE/g in the static TLM, 21,895 ± 3742 IE/g in the original TLM, and 6773 ± 735 IE/g in UW. In the human model, both the static TLM and the original TLM significantly increased islet yield compared with UW with postculture islet yields of 2659 ± 549 IE/g in the static TLM, 2244 ± 557 IE/g in the original TLM, and 1293 ± 451 IE/g in UW. Nonhuman primate and human pancreata stored in the static TLM, immediately upon procurement, yield isolated islets of a substantially higher quantity than when pancreata are stored in UW. Thus, the use of the static TLM should replace the use of UW for storage of pancreata during transport prior to islet isolation

Manufacturing differences affect human bone marrow stromal cell characteristics and function: comparison of production methods and products from multiple centers

Human bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) are manufactured using many different methods, but little is known about the spectrum of manufacturing methods used and their effects on BMSC characteristics and function. Seven centers using, and one developing, Good Manufacturing Practices (GMP) processes were surveyed as to their production methods. Among the seven centers, all used marrow aspirates as the starting material, but no two centers used the same manufacturing methods. Two to four BMSC lots from each center were compared using global gene expression. Among the twenty-four BMSC lots from the eight centers intra-center transcriptome variability was low and similar among centers. Principal component analysis and unsupervised hierarchical clustering analysis separated all the lots from five centers into five distinct clusters. BMSCs from six of the eight centers were tested for their ability to form bone and support hematopoiesis by in vivo transplantation (defining features of BMSCs). Those from all six centers tested formed bone, but the quantity formed was highly variable and BMSCs from only three centers supported hematopoiesis. These results show that differences in manufacturing resulted in variable BMSC characteristics including their ability to form bone and support hematopoiesis