Intracalvariosseous bone marrow injection detours the blood-brain barrier as a novel drug delivery approach for pre-clinic and clinic trials in stroke.

Central nervous system (CNS) accessibility constitutes a major hurdle for drug development to treat neurological diseases. Existing drug delivery methods mainly focus on opening the blood-brain barrier (BBB) to enhance penetration. Here we show that the inherent microchannels between the skull marrow and the dura mater could be harnessed for drug delivery by intracalvariosseous (ICO) injection. Drugs administered via ICO injection is found to reach cranial bone marrow-dura-perivascular space, and the injection procedure does not cause osteomyelitis or BBB damage. To validate this approach, we examined the efficacy of two neuroprotective agents NA-1 and Y-3 via ICO injection in stroke animal model, and found that ICO injection increases drug accumulation in the brain compared to intravenous injection, alleviates neurological damage after stroke, and reduces the infarction volume. We subsequently initiated a clinical trial to assess the feasibility and safety of ICO in stroke patients, namely "Y-3 Injection Through Skull Bone Marrow in the Treatment of Acute Malignant Middle Cerebral Artery Infarction (SOLUTION)" (ClinicalTrials.gov identifier [NCT05849805][1]), showing that ICO injection is feasible and safe in the human, therapeutic effects were also observed. Collectively our study identifies that the microchannels between the skull bone marrow and the dura mater as a new channel for CNS drug delivery to achieve high intracranial drug exposure in a short period of time. The safety of ICO injection makes it a promising therapy approach for CNS diseases. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT05849805 ### Funding Statement This study was funded by The National Natural Science Foundation of China (No. 81825007); Beijing Outstanding Young Scientist Program (No. BJJWZYJH01201910025030); Capital special Funds for Health Improvement and Research (2022-2-2045); National Key R&D Program of China (2022YFF1501500, 2022YFF1501501, 2022YFF1501502, 2022YFF1501503, 2022YFF1501504, 2022YFF1501505); Youth Beijing Scholar Program (No.010); Beijing Laboratory of Oral Health (PXM2021\_014226\_000041); Beijing Talent Project: Innovation and Development (No. 2018A12); National Ten-Thousand Talent Plan" Leadership of Scientific and Technological Innovation; National Key R&D Program of China (No. 2017YFC1307900, 2017YFC1307905). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Institutional Review Boards(IRB) of Beijing Tiantan Hospital, Capital Medical University, Beijing, China gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05849805&atom=%2Fmedrxiv%2Fearly%2F2024%2F03%2F05%2F2024.03.03.24303548.atom