Evaluation of vitamin D3 metabolites in Callithrix jacchus (common marmoset).

Vitamin D3 (cholecalciferol) is endogenously produced in the skin of primates when exposed to the appropriate wavelengths of ultraviolet light (UV-B). Common marmosets (Callithrix jacchus) maintained indoors require dietary provision of vitamin D3 due to lack of sunlight exposure. The minimum dietary vitamin D3 requirement and the maximum amount of vitamin D3 that can be metabolized by marmosets is unknown. Observations of metabolic bone disease and gastrointestinal malabsorption have led to wide variation in dietary vitamin D3 provision amongst research institutions, with resulting variation in circulating 25-hydroxyvitamin D3 (25(OH)D3 ), the accepted marker for vitamin D sufficiency/deficiency. Multiple studies have reported serum 25(OH)D3 in captive marmosets, but 25(OH)D3 is not the final product of vitamin D3 metabolism. In addition to serum 25(OH)D3, we measured the most physiologically active metabolite, 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), and the less well understood metabolite, 24,25-dihydroxyvitamin D3 (24,25(OH)2 D3 ) to characterize the marmoset's ability to metabolize dietary vitamin D3 . We present vitamin D3 metabolite and related serum chemistry value colony reference ranges in marmosets provided diets with 26,367 (Colony A, N = 113) or 8,888 (Colony B, N = 52) international units (IU) of dietary vitamin D3 per kilogram of dry matter. Colony A marmosets had higher serum 25(OH)D3 (426 ng/ml [SD 200] vs. 215 ng/ml [SD 113]) and 24,25(OH)2 D3 (53 ng/ml [SD 35] vs. 7 ng/ml [SD 5]). There was no difference in serum 1,25(OH)2 D3 between the colonies. Serum 1,25(OH)2 D3 increased and 25(OH)D3 decreased with age, but the effect was weak. Marmosets tightly regulate metabolism of dietary vitamin D3 into the active metabolite 1,25(OH)2 D3 ; excess 25(OH)D3 is metabolized into 24,25(OH)2 D3 . This ability explains the tolerance of high levels of dietary vitamin D3 by marmosets, however, our data suggest that these high dietary levels are not required.

Nanoparticle-mediated delivery of placental gene therapy via uterine artery catheterization in a pregnant rhesus macaque.

Nanoparticles offer promise as a mechanism to non-invasively deliver targeted placental therapeutics. Our previous studies utilizing intraplacental administration demonstrate efficient nanoparticle uptake into placental trophoblast cells and overexpression of human IGF1 ( hIGF1 ). Nanoparticle-mediated placental overexpression of hIGF1 in small animal models of placental insufficiency and fetal growth restriction improved nutrient transport and restored fetal growth. The objective of this pilot study was to extend these studies to the pregnant nonhuman primate and develop a method for local delivery of nanoparticles to the placenta via maternal blood flow from the uterine artery. Nanoparticles containing hIGF1 plasmid driven by the placenta-specific PLAC1 promoter were delivered to a mid-gestation pregnant rhesus macaque via a catheterization approach that is clinically used for uterine artery embolization. Maternal-fetal interface, fetal and maternal tissues were collected four days post-treatment to evaluate the efficacy of hIGF1 treatment in the placenta. The uterine artery catheterization procedure and nanoparticle treatment was well tolerated by the dam and fetus through the four-day study period following catheterization. Nanoparticles were taken up by the placenta from maternal blood as plasmid-specific hIGF1 expression was detected in multiple regions of the placenta via in situ hybridization and qPCR. The uterine artery catheterization approach enabled successful delivery of nanoparticles to maternal circulation in close proximity to the placenta with no concerns to maternal or fetal health in this short-term feasibility study. In the future, this delivery approach can be used for preclinical evaluation of the long-term safety and efficacy of nanoparticle-mediated placental therapies in a rhesus macaque model. Highlights: Novel method to deliver therapeutics to maternal-fetal interfaceDelivery of nanoparticles to the placenta via maternal catheterization.

Preclinical evaluation of transaxial intraputaminal trajectory for enhanced distribution of grafted cells in Parkinson's disease.

OBJECTIVE: The objective of this study was to develop and evaluate the feasibility and safety of a novel transaxial surgical approach for the delivery of human induced pluripotent stem cell-derived dopaminergic neuroprogenitor cells (DANPCs) into the putamen nucleus using nonhuman primates and surgical techniques and tools relevant to human clinical translation. METHODS: Nine immunosuppressed, unlesioned adult cynomolgus macaques (4 females, 5 males) received intraputaminal injections of vehicle or DANPCs (0.9 × 105 to 1.1 × 105 cells/µL) under real-time intraoperative MRI guidance. The infusates were combined with 1-mM gadoteridol (for intraoperative MRI visualization) and delivered via two tracks per hemisphere (ventral and dorsal) using a transaxial approach. The total volumes of infusion were 25 µL and 50 µL for the right and left putamen, respectively (infusion rate 2.5 µL/min). Animals were evaluated with a battery of clinical and behavioral outcome measures and euthanized 7 or 30 days postsurgery; full necropsies were performed by a board-certified veterinary pathologist. Brain tissues were collected and processed for immunohistochemistry, including against the human-specific marker STEM121. RESULTS: The optimized surgical technique and tools produced successful targeting of the putamen via the transaxial approach. Intraoperative MR images confirmed on-target intraputaminal injections in all animals. All animals survived to scheduled termination without clinical evidence of neurological deficits. The first 4 animals to undergo surgery had mild brain swelling noted at the end of surgery, of which 3 had transient reduced vision; administration of mannitol therapy and reduced intravenous fluid during the surgical procedure addressed these complications. Immunostaining against STEM121 confirmed the presence of grafted cells along the injection track within the targeted putamen area of DANPC-treated animals. All adverse histological findings were limited in scope and consistent with surgical manipulation, injection procedure, and postsurgical inflammatory response to the mechanical disruption caused by the cannula insertion. CONCLUSIONS: The delivery system, injection procedure, and DANPCs were well tolerated in all animals. Prevention of mild brain swelling by mannitol dosing and reduction of intravenous fluids during surgery allowed visual effects to be avoided. The results of the study established that this novel transaxial approach can be used to correctly and safely target cell injections to the postcommissural putamen and support clinical investigation.

Pharmacokinetics of Buprenorphine and Sustained-release Buprenorphine in Common Marmosets (Callithrix jacchus).

Buprenorphine is an essential component of analgesic protocols in common marmosets (Callithrix jacchus). The use of buprenorphine HCl (BUP) and sustained-release buprenorphine (BSR) formulations has become commonplace in this species, but the pharmacokinetics have not been evaluated. Healthy adult (age, 2.4 to 6.8 y; 6 female and 6 male) common marmosets were enrolled in this study to determine the pharmacokinetic parameters, plasma concentration-time curves, and any apparent adverse effects of these compounds. Equal numbers of each sex were randomly assigned to receive BUP (0.02 mg/kg IM) or BSR (0.2 mg/kg SC), resulting in peak plasma concentrations (mean ± 1 SD) of 15.2 ± 8.1 and 2.8 ± 1.2 ng/mL, terminal phase t1/2 of 2.2 ± 1.0 and 32.6 ± 9.6 h, and AUC0-last of 16.1 ± 3.7 and 98.6 ± 42.7 ng × h/mL. The plasma concentrations of buprenorphine exceeded the proposed minimal therapeutic threshold (0.1 ng/mL) at 5 and 15 min after BUP and BSR administration, showing that both compounds are rapid-acting, and remained above that threshold through the final time points of 8 and 72 h. Extrapolation of the terminal elimination phase of the mean concentration-time curves was used to develop the clinical dosing frequencies of 6 to 8 h for BUP and 3.0 to 3.5 d for BSR. Some adverse effects were observed after the administration of BUP to common marmosets in this study, thus mandating judicious use in clinical practice. BSR provided a safe, long-acting option for analgesia and therefore can be used to refine analgesic protocols in this species.

Current Topics in Marmoset Anesthesia and Analgesia.

Anesthetic and analgesics are essential components of both clinical and research procedures completed in marmosets. A review of current anesthetic and analgesic regimens for marmosets has been complied to provide a concise reference for veterinarians and investigator teams. Published dose regimens for injectable and inhalant anesthetic drugs and analgesic drugs are included. Appropriate physiological monitoring is key to the success of the procedure and perianesthetic options are provided. Although recent publications have refined anesthesia and analgesia practices, our review demonstrates the continued need for evidence-based resources specific to marmosets.

Clinical Management of Gastrointestinal Disease in the Common Marmoset (Callithrix jacchus).

Gastrointestinal disease is a frequently encountered problem among captive common marmoset (Callithrix jacchus) colonies. Management can be challenging due to the number of etiologies responsible for gastrointestinal disease in this species, limitations on diagnostic capabilities, and lack of effective treatments. Understanding commonly described GI diseases in the captive marmoset can provide insight on the impact these diseases have on research studies and aid in the development of appropriate management strategies. A review of commonly encountered GI disease processes as well as routinely implicated causes of GI disease in the common marmoset are provided. Current strategies in clinical management of GI disease in the common marmoset, including approaches to colony health, diagnostic testing, and commonly employed treatments are discussed.