Objectives: Long-acting nanoformulated antiretroviral therapy (nanoART) with improved pharmacokinetics, biodistribution and limited systemic toxicities will likely improve drug adherence and access to viral reservoirs. Design: Atazanavir and ritonavir crystalline nanoART were formulated in a poloxamer-188 excipient by high-pressure homogenization. These formulations were evaluated for antiretroviral and neuroprotective activities in humanized NOD/scid-IL-2Rg_c^null (NSG) mice. Methods: NanoART-treated NSG mice were evaluated for drug biodistribution, pharmacodynamics and toxicity. CD34⁺ human hematopoietic stem cells were transplanted at birth in replicate NSG mice. The mice were infected with HIV-1_ADA at 5 months of age. Eight weeks later, the infected animals were treated with weekly subcutaneous injections of nanoformulated ATV and RTV. Peripheral viral load, CD4⁺ T-cell counts and lymphoid and brain histopathology and immunohistochemistry tests were performed. Results: NanoART treatments by once-a-week injections reduced viral loads more than 1000-fold and protected CD4⁺ T-cell populations. This paralleled high ART levels in liver, spleen and blood that were in or around the human minimal effective dose concentration without notable toxicities. Importantly, examination of infected brain subregions showed that nanoART elicited neuroprotective responses with detectable increases in microtubule-associated protein-2, synaptophysin and neurofilament expression when compared to untreated virus-infected animals. Therapeutic interruptions produced profound viral rebounds. Conclusion: Long-acting nanoART has translational potential with sustained and targeted efficacy and with limited systemic toxicities. Such success in drug delivery and distribution could improve drug adherence and reduce viral resistance in infected people.

Human Immunodeficiency Virus Type 1 (HIV-1) remains one of the leading causes of death worldwide. Present combination antiretroviral therapy has substantially improved HIV-1 related pathology. However, delivery of therapeutic agents to the HIV reservoir organ like Central nervous system (CNS) remains a major challenge primarily due to the ineffective transmigration of drugs through Blood Brain Barrier (BBB). The recent advent of nanomedicine-based drug delivery has stimulated the development of innovative systems for drug delivery. In this regard, particular focus has been given to nanodiamond due to its natural biocompatibility and non-toxic nature–making it a more efficient drug carrier than other carbon-based materials. Considering its potential and importance, we have characterized unmodified and surface-modified (-COOH and -NH₂) nanodiamond for its capacity to load the anti-HIV-1 drug efavirenz and cytotoxicity,in vitro. Overall, our study has established that unmodified nanodiamond conjugated drug formulation has significantly higher drug loading capacity than surface-modified nanodiamond with minimum toxicity. Further, this nanodrug formulation was characterized by its drug dissolution profile, transmigration through the BBB, and its therapeutic efficacy. The present biological characterizations provide a foundation for further study ofin-vivopharmacokinetics and pharmacodynamics of nanodiamond-based anti-HIV drugs.

The constituents of highly active anti-retroviral therapy (HAART) include HIV-1 protease inhibitors (HPIs) and nucleoside reverse transcriptase inhibitors (NRTIs). Endothelial cell (EC) barriers, especially the blood-brain-barrier (BBB) suppresses the entry of HAART drugs to subendothelial HIV-1 reservoirs. The ATP binding cassette (ABC) transporter family members, multidrug resistant-1 (MDR-1) and multidrug resistance-associated proteins (MRPs) can efflux both HPIs and NRTIs from intracellular compartments. Using brain derived ECs from non-human sources, previous studies suggested a dominant role for MDR-1 in HAART efflux from the BBB. However, due to species variations in ABC-transporter expression, drug-efflux functions using human brain ECs need to be investigated. Furthermore, roles of ABC-transporters in drug-efflux from systemic EC barriers need to be studied. We monitored the expression of ABC-transporters in primary human ECs obtained from brain (HBMVECs), aorta (HAECs), pulmonary-artery (HPAECs), dermal-microvessel (HDMVECs) and umbilical vein (HUVECs). Gene expression for MDR-1 and MRPs (MRP-1 to MRP-5) were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). Drug efflux functions were determined by calcein retention assays. Intracellular accumulation of both³H-saqui-navir (an HPI) and³H-zidovudine (an NRTI) were also monitored in HAECs and HBMVECs. Both assays were carried out in presence of verapamil (20–60 μM) or MK-571 (12.5–50 μM) inhibitors of MDR-1 and MRPs, respectively in presence of verapamil or MK-571. The HBMVECs expressed higher levels of MRPs than MDR-1 and only MK-571 significantly ( P < 0.01) suppressed calcein efflux from these cells. However, both HAECs and HPAECs showed MDR-1 and MRP expression and calcein efflux was inhibited by both verapamil and MK-571. Both inhibitors suppressed³H-saqubinavir efflux from HAECs, but only MK-571 suppressed saquinavir efflux from HBMVECs. In both ECs,³H-zidovudine efflux was only suppressed by MK-571. Thus, primary human ECs, especially brain derived ECs, predominantly express MRPs and their specific inhibition may enhance HAART efficacy in subendothelial HIV-1 reservoirs.