Fertility-preserving myeloablative conditioning using single-dose CD117 antibody-drug conjugate in a rhesus gene therapy model.

Hematopoietic stem cell (HSC) gene therapy has curative potential; however, its use is limited by the morbidity and mortality associated with current chemotherapy-based conditioning. Targeted conditioning using antibody-drug conjugates (ADC) holds promise for reduced toxicity in HSC gene therapy. Here we test the ability of an antibody-drug conjugate targeting CD117 (CD117-ADC) to enable engraftment in a non-human primate lentiviral gene therapy model of hemoglobinopathies. Following single-dose CD117-ADC, a >99% depletion of bone marrow CD34 + CD90 + CD45RA- cells without lymphocyte reduction is observed, which results are not inferior to multi-day myeloablative busulfan conditioning. CD117-ADC, similarly to busulfan, allows efficient engraftment, gene marking, and vector-derived fetal hemoglobin induction. Importantly, ADC treatment is associated with minimal toxicity, and CD117-ADC-conditioned animals maintain fertility. In contrast, busulfan treatment commonly causes severe toxicities and infertility in humans. Thus, the myeloablative capacity of single-dose CD117-ADC is sufficient for efficient engraftment of gene-modified HSCs while preserving fertility and reducing adverse effects related to toxicity in non-human primates. This targeted conditioning approach thus provides the proof-of-principle to improve risk-benefit ratio in a variety of HSC-based gene therapy products in humans.

Pharmacokinetics and Efficacy of a Long-lasting, Highly Concentrated Buprenorphine Solution in Rats.

Buprenorphine (Bup) is an opioid analgesic that is commonly used in laboratory rodents to provide postoperative analgesia. However, dosing every 4 to 6 h is necessary to maintain an analgesic plasma concentration of the drug. A long lasting, highly concentrated veterinary formulation of Bup (LHC-Bup) has been used to provide prolonged analgesia in cats and nonhuman primates. In the current study, we evaluated the duration of efficacy of LHC-Bup to determine if this formulation would provide a similarly prolonged analgesia in rats. Drug concentrations were measured after subcutaneous injection of 0.5 mg/kg LHC-Bup in both male and female rats. Plasma levels were measured at 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, 48, and 72 h. Male and female rats had peak plasma levels of LHC-Bup at 90 ng/mL and 34 ng/mL, respectively, at 15 min after administration, with a steady decrease by 24 h to 0.7 ng/mL in males and 1.3 ng/mL in females. Mechanical pain tolerance was evaluated after LHC-Bup administration using a Randall-Selitto analgesiometer to assess paw withdrawal. Male rats had a significantly longer paw withdrawal time for up to 12 h after administration, and females had longer paw withdrawal times for up to 24 h. An experimental laparotomy model was then used to assess the clinical efficacy of LHC-Bup at 0.5 mg/kg. LHC-Bup treatment was associated with a greater total distance traveled, reduced time to retrieve a food treat, and reduced grooming from 3 to 12 h after surgery as compared with saline controls. Groups receiving LHC-Bup showed coprophagy whereas other rats did not. These results suggest that administering LHC-Bup at 0.5 mg/kg provides therapeutic plasma concentrations for 12 to 24 h after administration and analgesic efficacy for at least 12 h after dosing. As such, LHC-Bup is a suitable alternative to Bup-HCl.

Effects of Compressed Paper Bedding on Mouse Breeding Performance and Recognition of Animal Health Concerns.

The combination of bedding substrate and nesting material within the microenvironment of mice is an important consideration for animal care programs in regard to optimizing animal wellbeing. We used 3 general or breeding mouse colonies in our institution to evaluate the effects of bedding substrate on nest building, breeding performance, and recognition of animal health concerns. A scoring system was developed to assess the incorporation of bedding into the nest cup base and walls (nest base incorporation, NBI) in a controlled study with mice bedded on either compressed paper (CP) or corncob (CC) bedding. Compared with CC cages, CP cages had higher NBI scores. To determine the influence of bedding type on the recognition of animal health concerns in an animal facility, cages bedded with CC followed by CP were evaluated for the overall frequency of health-concern reports during a 2-mo time frame for each bedding type in a single-subject A-B study design. The frequency of animal health-concern reports was similar in cages using CC or CP bedding. The animal health condition, rather than bedding type, was associated with the severity of the health problem at the initial report. Breeding performance was compared for 6 mo in matched CC and CP cages containing one of 13 genetically modified mouse lines. NBI scores were higher for breeders housed on CP compared with CC bedding. Monogamous breeder pairs housed on CP had significantly higher indexes of breeding performance (measured as the number of pups per dam per week on study) than did CC cages. This report supports the use of CP bedding in the mouse microenvironment to improve general wellbeing by supporting nesting behavior and reproductive performance without hindering the detection of animal health concerns.

Effects of exercise in a relapsing-remitting model of experimental autoimmune encephalomyelitis.

Previous research has examined the effects of exercise in experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis. However, all previous studies have utilized a chronic model of EAE, with exercise delivered prior to or immediately after induction of EAE. To our knowledge, no study has examined the effects of exercise delivered during a remission period after initial disease onset in a relapsing-remitting model of EAE (RR-EAE). The current study examines the effects of both voluntary wheel running and forced treadmill exercise on clinical disability and hippocampal brain-derived neurotrophic factor (BDNF) in SJL mice with RR-EAE. The results demonstrate no significant effects of exercise delivered during remission after initial disease onset on clinical disability scores or levels of hippocampal BDNF in mice with RR-EAE. Furthermore, our results demonstrate no significant increase in citrate synthase activity in the gastrocnemius and soleus muscles of mice in the running wheel or treadmill conditions compared with the sedentary condition. These results suggest that the exercise stimuli might have been insufficient to elicit differences in clinical disability or hippocampal BDNF among treatment conditions. © 2016 Wiley Periodicals, Inc.