Variability and error in measurement of infant formula powder and water: an experimental study.

Introduction: Formula feeding is the only viable nutrition alternative for infants 0-6mos who cannot breastfeed. Among the drawbacks of formula feeding, however, is potential dilution or concentration errors in the formula during preparation that may lead to infant health issues. The present study aimed to investigate the accuracy of caregiver measurements as they prepared infant formula under multiple conditions, compared with manufacturer specifications. Methods: A diverse sample of caregivers (N = 84) participated in this cross-over experimental study. Participants hand-scooped infant formula powder and poured water to prepare 4oz. and 7oz. feedings, using both a standardized set of infant formula products and participants' own products. Linear mixed effects models were used to estimate fixed effects of target amount (4oz. versus 7oz) and products (participant versus researcher) on mean absolute percent error (MAPE) of measurement. Results: Across all conditions MAPE was significantly greater for measuring powder than for water (9.0% vs. 4.4%; p < 0.001) with a combined powder and water MAPE at 13.0%. Greater measurement error was associated with the odd-sized 7oz. preparation and participants' own products. Discussion: We observed considerable variability and substantial error during infant formula preparation, particularly for hand-scooping of powder, which tended toward higher values than the theoretical gold standard.

Peptide-guided lipid nanoparticles deliver mRNA to the neural retina of rodents and nonhuman primates.

Lipid nanoparticle (LNP)-based mRNA delivery holds promise for the treatment of inherited retinal degenerations. Currently, LNP-mediated mRNA delivery is restricted to the retinal pigment epithelium (RPE) and Müller glia. LNPs must overcome ocular barriers to transfect neuronal cells critical for visual phototransduction, the photoreceptors (PRs). We used a combinatorial M13 bacteriophage-based heptameric peptide phage display library for the mining of peptide ligands that target PRs. We identified the most promising peptide candidates resulting from in vivo biopanning. Dye-conjugated peptides showed rapid localization to the PRs. LNPs decorated with the top-performing peptide ligands delivered mRNA to the PRs, RPE, and Müller glia in mice. This distribution translated to the nonhuman primate eye, wherein robust protein expression was observed in the PRs, Müller glia, and RPE. Overall, we have developed peptide-conjugated LNPs that can enable mRNA delivery to the neural retina, expanding the utility of LNP-mRNA therapies for inherited blindness.

The effects of PEGylation on LNP based mRNA delivery to the eye.

Gene therapy is now an effective approach to treat many forms of retinal degeneration. Delivery agents that are cell-specific, allow for multiple dosing regimens, and have low immunogenicity are needed to expand the utility of gene therapy for the retina. We generated eight novel lipid nanoparticles (LNPs) ranging in size from 50 nm to 150 nm by changing the PEG content from 5% to 0.5%, respectively. Subretinal injections of LNP-mRNA encoding luciferase revealed that 0.5% PEG content within nanoparticles elicits the highest expression. Similar injections of LNP delivered cre mRNA into Ai9 mice revealed cell-specific protein expression in the retinal pigment epithelium (RPE), confirmed by fundus photography and immunohistochemistry of whole globe cross-sections. To investigate mechanisms of LNP delivery to the eye, we injected mCherry mRNA using the subretinal approach in apoE-/- and Mertk-/- mice. RPE transfection was observed in both mouse models suggesting that LNP intracellular delivery is not solely dependent on apolipoprotein adsorption or phagocytosis. To investigate LNP penetration, particles were delivered to the vitreous chamber via an intravitreal injection. The 0.5% PEG particles mediated the highest luciferase activity and expression was observed in the Müller glia, the optic nerve head and the trabecular meshwork, but failed to reach the RPE. Overall, particles containing less PEG (~150 nm in size) mediated the highest expression in the eye. Thus far, these particles successfully transfect RPE, Müller cells, the optic nerve head and the trabecular meshwork based on route of administration which can expand the utility of LNP-mediated gene therapies for the eye.