Keith Vogel

Human embryonic-stem-cell-derived cardiomyocytes regenerate non-human primate hearts

Pluripotent stem cells provide a potential solution to current epidemic rates of heart failure by providing human cardiomyocytes to support heart regeneration. Studies of human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) in small-animal models have shown favourable effects of this treatment. However, it remains unknown whether clinical-scale hESC-CM transplantation is feasible, safe or can provide sufficient myocardial regeneration. Here we show that hESC-CMs can be produced at a clinical scale (more than one billion cells per batch) and cryopreserved with good viability. Using a non-human primate model of myocardial ischaemia followed by reperfusion, we show that cryopreservation and intra-myocardial delivery of one billion hESC-CMs generates extensive remuscularization of the infarcted heart. The hESC-CMs showed progressive but incomplete maturation over a 3-month period. Grafts were perfused by host vasculature, and electromechanical junctions between graft and host myocytes were present within 2 weeks of engraftment. Importantly, grafts showed regular calcium transients that were synchronized to the host electrocardiogram, indicating electromechanical coupling. In contrast to small-animal models, non-fatal ventricular arrhythmias were observed in hESC-CM-engrafted primates. Thus, hESC-CMs can remuscularize substantial amounts of the infarcted monkey heart. Comparable remuscularization of a human heart should be possible, but potential arrhythmic complications need to be overcome.

Intraventricular Angiotensin Elicits Drinking in the Baboon

Summary Cannulas aimed at the lateral cerebral ventricles were surgically implanted in baboons. A-II (5 /xg/animal) or control injections were made on subsequent days and water intake recorded to determine the patency of the cannulas. We found that (a) baboons drink considerable water after the IVT administration of A-II, (b) the response diminishes but still persists with repeated A-II tests spread over a several-month interval, and (c) elevated drinking in response to the administration of A-II is a practical way to confirm the success of ventricular cannulation.

A simple alopecia scoring system for use in colony management of laboratory-housed primates.

Alopecia in captive primates continues to receive attention from animal care personnel and regulatory agencies. However, a method that enables personnel to reliably score alopecia over time and under various conditions has proven difficult to achieve.

Myelodysplasia in 2 Pig-Tailed Macaques (Macaca nemestrina) Associated With Retroviral Vector–Mediated Insertional Mutagenesis and Overexpression of HOXB4

Gammaretroviral vectors are an efficient means to effect gene therapy. However, genotoxicity from insertion at nonrandom sites can confer a competitive advantage to transduced cells, resulting in clonal proliferation or neoplasia. Six pig-tailed macaques (Macaca nemestrina) underwent total body irradiation and reconstitution with autologous stem cells genetically modified by a gammaretroviral vector overexpressing HOXB4. Two animals were euthanized owing to irradiation- or transplantation-associated toxicity, whereas the other 4 had successful reconstitution. Of the 4 macaques with successful reconstitution, 1 has no long-term follow-up information; 1 was euthanized owing to infection with simian varicella virus infection 18 months post–total body irradiation; and the 2 others are described herein as case Nos. 1 and 2. After being stable for 3 years, case No. 1 developed pancytopenia and petechiation, and after 2 years of stability case No. 2 developed anemia and thrombocytopenia. Despite therapy, the animals deteriorated and were euthanized. Gross findings included emaciation; case No. 1 also had hemorrhage, peritonitis, and cholecystitis. Histologically, bone marrow was hypercellular with predominately blast cells of all hematopoietic lineages, though with myeloid predominance, and with maturation arrest and blast cell dysplasia (myelodysplasia). Myelodysplasia was likely from a combination of insertional mutagenesis by the retroviral vector and overexpression of HOXB4. Consequences of myelodysplasia included the blood dyscrasias and, in case No. 1, hemorrhage, bacterial cholecystitis, hepatitis, and peritonitis.

A dual-purpose device for protecting brain implants of baboons.

A device is described which is relatively easy to construct and which can be used to protect brain implants affixed to the skull of large primates. The device is essentially a stainless steel ring cemented around the brain implant. A plexiglass dome can then be attached to the ring to protect the implant. Further, a second device can be constructed which attaches to the ring and which provides gentle leverage to the brain implant to remove adhered obturators.

Evidence for persistence of the SHIV reservoir early after MHC haploidentical hematopoietic stem cell transplantation

Allogeneic transplantation (allo-HCT) has led to the cure of HIV in one individual, raising the question of whether transplantation can eradicate the HIV reservoir. To test this, we here present a model of allo-HCT in SHIV-infected, cART-suppressed nonhuman primates. We infect rhesus macaques with SHIV-1157ipd3N4, suppress them with cART, then transplant them using MHC-haploidentical allogeneic donors during continuous cART. Transplant results in ~100% myeloid donor chimerism, and up to 100% T-cell chimerism. Between 9 and 47 days post-transplant, terminal analysis shows that while cell-associated SHIV DNA levels are reduced in the blood and in lymphoid organs post-transplant, the SHIV reservoir persists in multiple organs, including the brain. Sorting of donor-vs.-recipient cells reveals that this reservoir resides in recipient cells. Moreover, tetramer analysis indicates a lack of virus-specific donor immunity post-transplant during continuous cART. These results suggest that early post-transplant, allo-HCT is insufficient for recipient reservoir eradication despite high-level donor chimerism and GVHD.Allogeneic hematopoietic cell transplantation (allo-HCT) has led to the cure of HIV in one individual, but the underlying mechanisms are unclear. Here, the authors present a model of allo-HCT in SHIV-infected nonhuman primates and show that the SHIV reservoir persists in multiple tissues early after transplantation.