Biodistribution of Lipid 5, mRNA, and Its Translated Protein Following Intravenous Administration of mRNA-Encapsulated Lipid Nanoparticles in Rats

RNA-based therapeutics and vaccines represent a novel and expanding class of medicines, the success of which depends on the encapsulation and protection of mRNA molecules in lipid nanoparticle (LNP)-based carriers. With the development of mRNA-LNP modalities, which can incorporate xenobiotic constituents, extensive biodistribution analyses are necessary to better understand the factors that influence their in vivo exposure profiles. This study investigated the biodistribution of heptadecan-9-yl 8-((2-hydroxyethyl)(8-(nonyloxy)-8-] oxooctyl)amino)octanoate (Lipid 5)-a xenobiotic amino lipid- and its metabolites in male and female pigmented (Long-Evans) and nonpigmented (Sprague Dawley) rats by using quantitative whole-body autoradiography (QWBA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. After intravenous injection of Lipid 5-containing LNPs, 14C-containing Lipid 5 ([14C]Lipid 5) and radiolabeled metabolites ([14C]metabolites) were rapidly distributed, with peak concentrations reached within 1 hour in most tissues. After 10 hours, [14C]Lipid 5 and [14C]metabolites concentrated primarily in the urinary and digestive tracts. By 24 hours, [14C]Lipid 5 and [14C]metabolites were localized almost exclusively in the liver and intestines, with few or no concentrations detected in non-excretory systems, which is suggestive of hepatobiliary and renal clearance. [14C]Lipid 5 and [14C]metabolites were completely cleared within 168 hours (7 days). Biodistribution profiles were similar between QWBA and LC-MS/MS techniques, pigmented and nonpigmented rats, and male and female rats, excluding the reproductive organs. In conclusion, the rapid clearance through known excretory systems, with no evidence of redistribution for Lipid 5 or accumulation of [14C]metabolites, provides confidence for the safe and effective use of Lipid 5-containing LNPs. Significance Statement This study demonstrates the rapid, systemic distribution of intact and radiolabeled metabolites of Lipid 5, a xenobiotic amino lipid component of novel mRNA-LNP medicines, and its effective clearance without substantial redistribution after intravenous administration; additionally, findings were consistent between different mRNAs encapsulated within LNPs of similar composition. This study confirms the applicability of current analytical methods for lipid biodistribution analyses, and taken together with appropriate safety studies, supports the continued use of Lipid 5 in mRNA-medicines.

341 Alder Hey Experience of Paediatric Virtual Fracture Clinic During The COVID-19 Pandemic

Introduction

The SARS-CoV2/COVID-19 pandemic represented an unprecedented emergency prompting a drive to minimise non-essential patient contact and the need for a virtual fracture clinic (VFC); an uncommon practice in paediatric units. Management of paediatric fractures requires a greater degree of vigilance to safeguard children. The current climate has created social challenges that theoretically increase the risk of harm and exploitation to children. This study investigates VFC in the management of paediatric fractures to determine the efficiency of such a process and the risk of safeguarding.

Method

A protocol was devised in affiliation with BSCOS for the immediate management and streamlining of paediatric fractures into VFC. We retrospectively audited 235 VFC consults over a 1-month period. Patient sex was roughly evenly distributed, and age ranged from 9 months to 16 years (mean 8.4 years).

Results

42% of patients were recalled for a face-to-face (F2F) review (26% expedited), primarily for clinical assessment, plaster complaints and imaging requirements. 33% were discharged and 15% continued follow-up in VFC. All clavicle fractures were discharged. Forearm, hand, foot and elbow injuries were more likely to be discharged. Lower leg, upper arm and knee presentations more frequently required a F2F review. 2.3% of cases required safeguarding reviews.

Conclusions

Given the rapid transition to VFC without the use of triage we have determined a number of non-complex fractures safely managed and discharged via VFC. The low percentage of recall due to safeguarding concern highlights this may not be a barrier to the continuation of virtual care outside of the context of a pandemic.

Synthetic human ABCB4 mRNA therapy rescues severe liver disease phenotype in a BALB/c.Abcb4-/- mouse model of PFIC3

BACKGROUND & AIMS

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare lethal autosomal recessive liver disorder caused by loss-of-function variations of the ABCB4 gene, encoding a phosphatidylcholine transporter (ABCB4/MDR3). Currently, no effective treatment exists for PFIC3 outside of liver transplantation.

METHODS

We have produced and screened chemically and genetically modified mRNA variants encoding human ABCB4 (hABCB4 mRNA) encapsulated in lipid nanoparticles (LNPs). We examined their pharmacological effects in a cell-based model and in a new in vivo mouse model resembling human PFIC3 as a result of homozygous disruption of the Abcb4 gene in fibrosis-susceptible BALB/c.Abcb4-/- mice.

RESULTS

We show that treatment with liver-targeted hABCB4 mRNA resulted in de novo expression of functional hABCB4 protein and restored phospholipid transport in cultured cells and in PFIC3 mouse livers. Importantly, repeated injections of the hABCB4 mRNA effectively rescued the severe disease phenotype in young Abcb4-/- mice, with rapid and dramatic normalisation of all clinically relevant parameters such as inflammation, ductular reaction, and liver fibrosis. Synthetic mRNA therapy also promoted favourable hepatocyte-driven liver regeneration to restore normal homeostasis, including liver weight, body weight, liver enzymes, and portal vein blood pressure.

CONCLUSIONS

Our data provide strong preclinical proof-of-concept for hABCB4 mRNA therapy as a potential treatment option for patients with PFIC3.

LAY SUMMARY

This report describes the development of an innovative mRNA therapy as a potential treatment for PFIC3, a devastating rare paediatric liver disease with no treatment options except liver transplantation. We show that administration of our mRNA construct completely rescues severe liver disease in a genetic model of PFIC3 in mice.

Technologies and Standardization in Research on Extracellular Vesicles

Extracellular vesicles (EVs) are phospholipid bilayer membrane-enclosed structures containing RNAs, proteins, lipids, metabolites, and other molecules, secreted by various cells into physiological fluids. EV-mediated transfer of biomolecules is a critical component of a variety of physiological and pathological processes. Potential applications of EVs in novel diagnostic and therapeutic strategies have brought increasing attention. However, EV research remains highly challenging due to the inherently complex biogenesis of EVs and their vast heterogeneity in size, composition, and origin. There is a need for the establishment of standardized methods that address EV heterogeneity and sources of pre-analytical and analytical variability in EV studies. Here, we review technologies developed for EV isolation and characterization and discuss paths toward standardization in EV research.

Long-term glycemic control using polymer-encapsulated human stem cell-derived beta cells in immune-competent mice

The transplantation of glucose-responsive, insulin-producing cells offers the potential for restoring glycemic control in individuals with diabetes. Pancreas transplantation and the infusion of cadaveric islets are currently implemented clinically, but these approaches are limited by the adverse effects of immunosuppressive therapy over the lifetime of the recipient and the limited supply of donor tissue. The latter concern may be addressed by recently described glucose-responsive mature beta cells that are derived from human embryonic stem cells (referred to as SC-β cells), which may represent an unlimited source of human cells for pancreas replacement therapy. Strategies to address the immunosuppression concerns include immunoisolation of insulin-producing cells with porous biomaterials that function as an immune barrier. However, clinical implementation has been challenging because of host immune responses to the implant materials. Here we report the first long-term glycemic correction of a diabetic, immunocompetent animal model using human SC-β cells. SC-β cells were encapsulated with alginate derivatives capable of mitigating foreign-body responses in vivo and implanted into the intraperitoneal space of C57BL/6J mice treated with streptozotocin, which is an animal model for chemically induced type 1 diabetes. These implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control. Implants retrieved after 174 d contained viable insulin-producing cells.

Combination wt-p53 and MicroRNA-125b Transfection in a Genetically Engineered Lung Cancer Model Using Dual CD44/EGFR-targeting Nanoparticles

Mutations in KRAS and p53 signaling pathways contribute to loss of responsiveness to current therapies and a decreased survival in lung cancer. In this study, we have investigated the delivery and transfection of wild-type (wt-) p53 and microRNA-125b (miR-125b) expressing plasmid DNA, in SK-LU-1 human lung adenocarcinoma cells as well as in Kras(G12D)/p53(fl/fl) (KP) genetically engineered mouse model of lung cancer. Systemic plasmid DNA delivery with dual CD44/EGFR-targeted hyaluronic acid (HA)-based nanoparticles (NPs) resulted in a 2- to 20-fold increase in wt-p53 and miR-125b gene expression in SK-LU-1 cells. This resulted in enhanced apoptotic activity as seen with increased APAF-1 and caspase-3 gene expression. Similarly, in vivo evaluations in KP mouse model indicated successful CD44/EGFR-targeted delivery. Tumor growth inhibition and apoptotic induction were also observed with (wt-p53+miR125b) combination therapy in KP tumor model. Lastly, J774.A1 murine macrophages co-cultured with transfected SK-LU-1 cells showed a 14- to 35-fold increase in the iNOS-Arg-1 ratio, supportive of previous results demonstrating a role of miR-125b in macrophage repolarization. Overall, these results show tremendous promise of wt-p53 and miR-125b gene therapy using dual CD44/EGFR-targeting HA NP vector for effective treatment of lung cancer.

Comparative analysis of BU and CY versus CY and TBI in full intensity unrelated marrow donor transplantation for AML, CML and myelodysplasia

We retrospectively compared clinical outcomes in 1593 T-replete unrelated donor (URD) marrow transplant recipients with AML, MDS and CML who received myeloablative conditioning regimens of either BU and CY (BuCy), standard-dose Cy/TBI (1000-1260 cGy) or high-dose Cy/TBI (1320-1500 cGy). Subjects were drawn from patients transplanted between 1991 and 1999 facilitated by the National Marrow Donor Program. Patients who received high-dose Cy/TBI regimens were slightly younger, more likely to receive a mismatched transplant and to have intermediate or advanced disease compared with patients in the BuCy or standard-dose TBI group. Neutrophil recovery was significantly higher in the standard-dose CY/TBI group compared with the high-dose Cy/TBI or BuCy group. Patients who received the high-dose Cy/TBI regimen had an increased risk of developing grades III-IV aGVHD when compared with the control group who received BuCy (P = 0.011). OS, disease-free survival (DFS), TRM and relapse were not significantly different between any of the regimens. We conclude that BuCy, standard-dose and high-dose Cy/TBI regimens have equivalent efficacy profiles for OS, DFS, TRM and relapse risk in patients undergoing T-replete URD marrow transplantation for AML, CML and MDS.

Effects of topical mitomycin C on primary trabeculectomies and combined procedures

The charts were reviewed of all patients who underwent primary trabeculectomies (group 1) or combined procedures (phacoemulsification + intraocular lens implantation + trabeculectomy--group 2) and received intraoperative mitomycin C (0.4 mg/ml) between 1991 and 1992 at Wills Eye Hospital. A total of 54 eyes of 54 patients were included: 39 in group 1 and 15 in group 2. Intraocular pressure was controlled successfully in 97.4% of eyes in group 1 (mean follow up 6.7 months), and in 93.3% in group 2 (mean follow up 6.8 months). Main complications included choroidal detachment (n = 15), shallow anterior chamber (n = 9), cataract formation (n = 8), and hypotony maculopathy (n = 3). The use of mitomycin C in primary trabeculectomies and combined procedures is associated with high success rates. However, it may be associated with unacceptable risks of vision threatening complications related to excessive filtration.

Primary trabeculectomy in young adults

BACKGROUND

Younger patients are thought to have a poor surgical prognosis after trabeculectomy. The authors investigate the surgical outcome of young adult patients after primary trabeculectomy.

METHODS

The authors reviewed the charts of all patients 15 to 40 years of age who had undergone primary trabeculectomy without the use of antimetabolites between January 1985 and January 1992 at Wills Eye Hospital. Failure was defined before the data collection as intraocular pressure (IOP) more than 25 mmHg without medication, IOP more than 21 mmHg with medication, or when further glaucoma surgery was indicated. Patients in whom preoperative IOPs were 21 mmHg or lower were classified as successes when the IOP was reduced by at least 33% of the preoperative measurement.

RESULTS

After a mean follow-up of 36.8 +/- 21.8 months, among the 31 patients with uncomplicated glaucomas (juvenile, pigmentary, low tension, chronic angle closure), 26 (83.9%) were considered successes. After a mean follow-up of 42.3 +/- 26.5 months, among the 11 patients with other types of glaucoma (inflammatory, traumatic, associated with irido-corneal endothelial syndrome or mesodermal dysgenesis), 7 (63.6%) were considered successes.

CONCLUSIONS

The success rate of the uncomplicated group compares favorably with the 75% to 90% success rates of trabeculectomy commonly cited for primary glaucomas in older patients. Primary trabeculectomy in young adults may have a favorable outcome despite no antimetabolite therapy.

Hypotony maculopathy following the use of topical mitomycin C in glaucoma filtration surgery

Intraoperative mitomycin C has been shown to be highly effective in increasing the success rate of glaucoma filtration surgery. Between October 1991 and June 1992, 169 eyes of 156 patients underwent filtration procedures with intraoperative mitomycin C. In the postoperative period, five eyes (2.9%) developed hypotony maculopathy, characterized by disc edema, vascular tortuosity, and chorioretinal folds in the macular area. Cryotherapy was applied to three eyes, and was effective in reversing the hypotony in two of them. However, the visual prognosis was poor: after a mean follow up of 5.3 months (range, 3.5 to 8 months), visual acuity returned to preoperative levels in one case. Hypotony maculopathy may develop after glaucoma filtration surgery with intraoperative mitomycin C. We suggest restricting the indication of its adjunctive use to eyes with poor surgical prognosis or those in which a very low intraocular pressure is desired. The use of extra sutures (which can be sectioned by laser) or releasable sutures to prevent excessive filtration in the postoperative period also is advisable.

Loss of visual acuity after trabeculectomy

BACKGROUND

Glaucoma filtration surgery can result in loss of visual acuity by a variety of mechanisms. The existence of "wipe-out" (loss of the central visual field in the absence of other explanation) as a cause of postoperative loss of visual acuity has been debated. This study defines the incidence and etiology of visual acuity loss within 3 months of trabeculectomy.

METHODS

The authors reviewed 508 eyes of 440 patients who underwent trabeculectomy to find cases of postoperative visual acuity loss (2 or more Snellen lines or a category change) and randomly selected a control group of 85 eyes to analyze the risk factors for each cause of visual acuity loss.

RESULTS

Forty-two eyes (8.3%) showed loss of visual acuity after 3 months, caused mainly by lens opacification (n = 16), hypotony maculopathy (n = 6), and "wipe-out" (n = 4). Older patients (P = 0.0108), those in whom the visual field preoperatively showed macular splitting (P = 0.0084) and those who had severe hypotony (intraocular pressure [IOP] < or = 2 mmHg) on the first postoperative day (P = 0.0246) were more likely to experience "wipe-out." Older age (P = 0.0495) and shallow anterior chamber (P = 0.0003) were correlated to the development of lens opacification. Hypotony maculopathy was associated with coronary artery disease (P = 0.0397) and systemic hypertension (P = 0.0118).

CONCLUSIONS

Lens opacification was the main cause of early visual acuity loss after trabeculectomy, followed by hypotony maculopathy. "Wipe-out," although rare, does exist, and older patients with advanced visual field defects are at increased risk.