The lung employs an intrinsic surfactant-mediated inflammatory response for viral defense.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) causes an acute respiratory distress syndrome (ARDS) that resembles surfactant deficient RDS. Using a novel multi-cell type, human induced pluripotent stem cell (hiPSC)-derived lung organoid (LO) system, validated against primary lung cells, we found that inflammatory cytokine/chemokine production and interferon (IFN) responses are dynamically regulated autonomously within the lung following SARS-CoV-2 infection, an intrinsic defense mechanism mediated by surfactant proteins (SP). Single cell RNA sequencing revealed broad infectability of most lung cell types through canonical (ACE2) and non-canonical (endocytotic) viral entry routes. SARS-CoV-2 triggers rapid apoptosis, impairing viral dissemination. In the absence of surfactant protein B (SP-B), resistance to infection was impaired and cytokine/chemokine production and IFN responses were modulated. Exogenous surfactant, recombinant SP-B, or genomic correction of the SP-B deletion restored resistance to SARS-CoV-2 and improved viability.

A Biomarker for Predicting Responsiveness to Stem Cell Therapy Based on Mechanism-of-Action: Evidence from Cerebral Injury.

To date, no stem cell therapy has been directed to specific recipients-and, conversely, withheld from others-based on a clinical or molecular profile congruent with that cell's therapeutic mechanism-of-action (MOA) for that condition. We address this challenge preclinically with a prototypical scenario: human neural stem cells (hNSCs) against perinatal/neonatal cerebral hypoxic-ischemic injury (HII). We demonstrate that a clinically translatable magnetic resonance imaging (MRI) algorithm, hierarchical region splitting, provides a rigorous, expeditious, prospective, noninvasive "biomarker" for identifying subjects with lesions bearing a molecular profile indicative of responsiveness to hNSCs' neuroprotective MOA. Implanted hNSCs improve lesional, motor, and/or cognitive outcomes only when there is an MRI-measurable penumbra that can be forestalled from evolving into necrotic core; the core never improves. Unlike the core, a penumbra is characterized by a molecular profile associated with salvageability. Hence, only lesions characterized by penumbral > core volumes should be treated with cells, making such measurements arguably a regenerative medicine selection biomarker.

Transplantation of Human Neural Progenitor Cells Reveals Structural and Functional Improvements in the Spastic Han-Wistar Rat Model of Ataxia.

The use of regenerative medicine to treat nervous system disorders like ataxia has been proposed to either replace or support degenerating neurons. In this study, we assessed the ability of human neural progenitor cells (hNPCs) to repair and restore the function of dying neurons within the spastic Han-Wistar rat (sHW), a model of ataxia. The sHW rat suffers from neurodegeneration of specific neurons, including cerebellar Purkinje cells and hippocampal CA3 pyramidal cells leading to the observed symptoms of forelimb tremor, hind-leg rigidity, gait abnormality, motor incoordination, and a shortened life span. To alleviate the symptoms of neurodegeneration and to replace or augment dying neurons, neuronal human progenitor cells were implanted into the sHW rats. At 30 d of age, male sHW mutant rats underwent subcutaneous implantation of an Alzet osmotic pump that infused cyclosporine (15 mg/kg/d) used to suppress the rat's immune system. At 40 d, sHW rats received bilateral injections (500,000 cells in 5 µL media) of live hNPCs, dead hNPCs, live human embryonic kidney cells, or growth media either into the cerebellar cortex or into the hippocampus. To monitor results, motor activity scores (open-field testing) and weights of the animals were recorded weekly. The sHW rats that received hNPC transplantation into the cerebellum, at 60 d of age, displayed significantly higher motor activity scores and sustained greater weights and longevities than control-treated sHW rats or any hippocampal treatment group. In addition, cerebellar histology revealed that the transplanted hNPCs displayed signs of migration and signs of neuronal development in the degenerated Purkinje cell layer. This study revealed that implanted human progenitor cells reduced the ataxic symptoms in the sHW rat, identifying a future clinical use of these progenitor cells against ataxia and associated neurodegenerative diseases.

Efficacy of Two Delivery Routes for Transplanting Human Neural Progenitor Cells (NPCs) Into the Spastic Han-Wistar Rat, a Model of Ataxia.

An emerging avenue for recalcitrant neurodegenerative disease treatment is neural progenitor cell (NPC) transplantation. In this study, we investigated the effectiveness of two different delivery routes of human-derived NPC inoculation: injection into the common carotid artery or unilateral stereotactic implantation into the degenerating cerebellum and hippocampus of spastic Han-Wistar (sHW) rats, a model of ataxia. At 30 days of age, sHW mutants were implanted with osmotic pumps preloaded with cyclosporine. Ten days after pump implantation, the animals were given either 3,000,000 live human-derived NPCs (hNPCs; n = 12) or 3,000,000 dead NPCs (dNPCs; n = 12) injected into the common carotid artery, or were given two unilateral implantations of 500,000 hNPCs into the cerebellum and 500,000 hNPCs into the hippocampus of each sHW rat (n = 12) or 500,000 dNPCs by unilateral implantation into the cerebellum and hippocampus (n = 12). We also compared treated sHW rats to untreated sHW rats: normal rats (n = 12) and sibling sHW rats (n = 12). Motor activity and animal weights were monitored every 5 days to ascertain effectiveness of the two types of delivery methods compared to the untreated mutant and normal animals. Mutant rats with hNPC implantations, but not dNPC or carotid artery injections, showed significant deceleration of motor deterioration (p < 0.05). These mutants with hNPC implantations also retained weight longer than dNPC mutants did (p < 0.05). At the end of the experiment, animals were sacrificed for histological evaluation. Using fluorescent markers (Qtracker) incorporated into the hNPC prior to implantation and human nuclear immunostaining, we observed few hNPCs in the brains of carotid artery-injected mutants. However, significant numbers of surviving hNPCs were seen using these techniques in mutant cerebellums and hippocampi implanted with hNPC. Our results show that direct implantation of hNPCs reduced ataxic symptoms in the sHW rat, demonstrating that stereotactic route of stem cell delivery correlates to improved clinical outcomes.