Subcutaneous Administration of a Zwitterionic Chitosan-Based Hydrogel for Controlled Spatiotemporal Release of Monoclonal Antibodies

Subcutaneous (SC) administration of monoclonal antibodies (mAbs) is a proven strategy for improving therapeutic outcomes and patient compliance. The current FDA-/EMA-approved enzymatic approach, utilizing recombinant human hyaluronidase (rHuPH20) to enhance mAbs SC delivery, involves degrading the extracellular matrix's hyaluronate to increase tissue permeability. However, this method lacks tunable release properties, requiring individual optimization for each mAb. Seeking alternatives, physical polysaccharide hydrogels emerge as promising candidates due to their tunable physicochemical and biodegradability features. Unfortunately, none have demonstrated simultaneous biocompatibility, biodegradability, and controlled release properties for large proteins (≥150 kDa) after SC delivery in clinical settings. Here, a novel two-component hydrogel comprising chitosan and chitosan@DOTAGA is introduced that can be seamlessly mixed with sterile mAbs formulations initially designed for intravenous (IV) administration, repurposing them as novel tunable SC formulations. Validated in mice and nonhuman primates (NHPs) with various mAbs, including trastuzumab and rituximab, the hydrogel exhibited biodegradability and biocompatibility features. Pharmacokinetic studies in both species demonstrated tunable controlled release, surpassing the capabilities of rHuPH20, with comparable parameters to the rHuPH20+mAbs formulation. These findings signify the potential for rapid translation to human applications, opening avenues for the clinical development of this novel SC biosimilar formulation.

Mechanistic Insights into Hyaluronic Acid Induced Peptide Nanofiber Organization in Supramolecular Hydrogels

Composite hydrogels composed of low-molecular-weight peptide self-assemblies and polysaccharides are gaining great interest as new types of biomaterials. Interactions between polysaccharides and peptide self-assemblies are well reported, but a molecular picture of their impact on the resulting material is still missing. Using the phosphorylated tripeptide precursor Fmoc-FFpY (Fmoc, fluorenylmethyloxycarbonyl; F, phenylalanine; Y, tyrosine; p, phosphate group), we investigated how hyaluronic acid (HA) influences the enzyme-assisted self-assembly of Fmoc-FFY generated in situ in the presence of alkaline phosphatase (AP). In the absence of HA, Fmoc-FFY peptides are known to self-assemble in nanometer thick and micrometer long fibers. The presence of HA leads to the spontaneous formation of bundles of several micrometers thickness. Using fluorescence recovery after photobleaching (FRAP), we find that in the bundles both (i) HA colocalizes with the peptide self-assemblies and (ii) its presence in the bundles is highly dynamic. The attractive interaction between negatively charged peptide fibers and negatively charged HA chains is explained through molecular dynamic simulations that show the existence of hydrogen bonds. Whereas the Fmoc-FFY peptide self-assembly itself is not affected by the presence of HA, this polysaccharide organizes the peptide nanofibers in a nematic phase visible by small-angle X-ray scattering (SAXS). The mean distance d between the nanofibers decreases by increasing the HA concentration c, but remains always larger than the diameter of the peptide nanofibers, indicating that they do not interact directly with each other. At a high enough HA concentration, the nematic organization transforms into an ordered 2D hexagonal columnar phase with a nanofiber distance d of 117 Å. Depletion interaction generated by the polysaccharides can explain the experimental power law variation d ∼ c - 1 / 4 and is responsible for the bundle formation and organization. Such behavior is thus suggested for the first time on nano-objects using polymers partially adsorbing on self-assembled peptide nanofibers.

Tear of lipid membranes by nanoparticles

Health concerns associated with the advent of nanotechnologies have risen sharply when it was found that particles of nanoscopic dimensions reach the cell lumina. Plasma and organelle lipid membranes, which are exposed to both the incoming and the engulfed nanoparticles, are the primary targets of possible disruptions. However, reported adhesion, invagination and embedment of nanoparticles (NPs) do not compromise the membrane integrity, precluding direct bilayer damage as a mechanism for toxicity. Here it is shown that a lipid membrane can be torn by small enough nanoparticles, thus unveiling mechanisms for how lipid membrane can be compromised by tearing from nanoparticles. Surprisingly, visualization by cryo transmission electron microscopy (cryo-TEM) of liposomes exposed to nanoparticles revealed also that liposomal laceration is prevented by particle abundance. Membrane destruction results thus from a subtle particle-membrane interplay that is here elucidated. This brings into a firmer molecular basis the theorized mechanisms of nanoparticle effects on lipid bilayers and paves the way for a better assessment of nanoparticle toxicity.

Gel-to-gel non-variant transition of an organogel caused by polymorphism from nanotubes to crystallites

An amide based gelator forms gels in trans-decalin. Below concentrations of 1 wt% the gels melt at temperatures varying with concentration. Above a concentration of 1 wt%, upon heating, the gel transforms into an opaque gel at an invariant temperature, and melts at higher temperature. The gel-to-gel transition is evidenced by several techniques: DSC, rheology, NMR, OM and turbidimetry. The phase diagram with the domain of the existence of both morphs was mapped by these techniques. Optical and electronic microscopy studies show that the first gel corresponds to the self-assembled nanotubes while the second gel is formed by crystalline fibers. The fibers are crystalline, as shown by the presence of Bragg peaks in the scattering curves. Both morphs correspond to a different H-bonding pattern as shown by FTIR. The first gel forms at a higher cooling rate, is metastable and transforms slowly into the second one. The second gel is stable. It forms at a low cooling rate, or by thermal annealing or aging of the first gel.

Structure of Nanotubes Self-Assembled from a Monoamide Organogelator

Some organic compounds are known to self-assemble into nanotubes in solutions, but the packing of the molecules into the walls of the tubes is known only in a very few cases. Herein, we study two compounds forming nanotubes in alkanes. They bear a secondary alkanamide chain linked to a benzoic acid propyl ester (HUB-3) or to a butyl ester (HUB-4). They gel alkanes for concentrations above 0.2 wt.%. The structures of these gels, studied by freeze fracture electron microscopy, exhibit nanotubes: for HUB-3 their external diameters are polydisperse with a mean value of 33.3 nm; for HUB-4, they are less disperse with a mean value of 25.6 nm. The structure of the gel was investigated by small- and wide-angle X-ray scattering. The evolution of the intensities show that the tubes are metastable and transit slowly toward crystals. The intensities of the tubes of HUB-4 feature up to six oscillations. The shape of the intensities proves the tubular structure of the aggregates, and gives a measurement of 20.6 nm for the outer diameters and 11.0 nm for the inner diameters. It also shows that the electron density in the wall of the tubes is heterogeneous and is well described by a model with three layers.

Polyelectrolytes and small angle scattering

We present an introduction to the application of small angle Xray and neutron scattering to the study of polyelectrolyte solutions. We aim to give a simple overview of the structural information that can be gained with these techniques. In particular, we show how neutron scattering associated to isotopic labelling enables the determination of the different partial structure functions as well as the dispersion state and the average conformation of polyions.

The fluctuating ribosome: thermal molecular dynamics characterized by neutron scattering

Conformational changes associated with ribosome function have been identified by X-ray crystallography and cryo-electron microscopy. These methods, however, inform poorly on timescales. Neutron scattering is well adapted for direct measurements of thermal molecular dynamics, the ‘lubricant’ for the conformational fluctuations required for biological activity. The method was applied to compare water dynamics and conformational fluctuations in the 30 S and 50 S ribosomal subunits from Haloarcula marismortui, under high salt, stable conditions. Similar free and hydration water diffusion parameters are found for both subunits. With respect to the 50 S subunit, the 30 S is characterized by a softer force constant and larger mean square displacements (MSD), which would facilitate conformational adjustments required for messenger and transfer RNA binding. It has been shown previously that systems from mesophiles and extremophiles are adapted to have similar MSD under their respective physiological conditions. This suggests that the results presented are not specific to halophiles in high salt but a general property of ribosome dynamics under corresponding, active conditions. The current study opens new perspectives for neutron scattering characterization of component functional molecular dynamics within the ribosome.

Dynamics of nanoscale polarization fluctuations in a uniaxial relaxor

We have studied neutron diffuse scattering in a Sr(0.61)Ba(0.39)Nb(2)O(6) single crystal by neutron backscattering at sub-μeV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells.

From chain collapse to new structures: spectroscopic properties of poly(3-thiophene acetic acid) upon binding by alkyl trimethylammonium bromide surfactants

The binding of cationic surfactants with varying alkyl chain length to a regiorandom conjugated polyanion, poly(3-thiophene acetic acid) (PTAA), is studied in an aqueous buffer by using absorption and emission spectroscopies, photon correlation spectroscopy, isothermal titration calorimetry, and cryogenic transmission electron microscopy. We study the mixed solutions as a function of composition ratio R of surfactant molecules to monomer units molar concentrations, at low polymer concentration and in a very wide composition range (10(-6) < R < 10(2)) below the critical micellar concentration. Upon surfactant binding, the molecularly dispersed chains first collapse progressively and then form new structures as the mixed aggregates get enriched in surfactant. The collapse leads to a strong decrease of the conjugation length and to a blue shift of the absorption spectra by 30 to 50 nm. The new structures are responsible for a new intense emission band at about 600 nm, red-shifted by nearly 130 nm from the initial emission maximum of the polymer (~472 nm). As the surfactant tail becomes shorter, the blue shift of the absorption spectra and the intensity raise of the new emission are delayed to larger composition ratios while their variations become smoother functions of the surfactant concentration. These particular spectroscopic properties of PTAA seem related to its unique combination of a strongly hydrophobic backbone, a large ratio of contour length to persistence length, and an overall good aqueous solubility. Our results show that such features are well suited to design a colorimetric biosensor at small composition ratio, and a fluorescent biomarker at large composition ratio.

Alanine metabolism in isolated human kidney tubules--Use of a mathematical model

To gain insight into the fate of alanine nitrogen and carbon taken up by the human kidney under certain conditions, isolated human kidney cortex tubules were incubated in Krebs-Henseleit medium with L-alanine as substrate. The tubules metabolized alanine at high rates and in a dose-dependent manner. Most of the alanine nitrogen removed was recovered as ammonia and to a lesser extent as glutamate. Glucose, lactate and glutamate were also found to be significant products of alanine carbon metabolism. A simple mathematical model allowing one to calculate flux of alanine carbon through the various metabolic steps involved is proposed and applied to data obtained in experiments in which 5 mM [U-14C]-,[1-14C]-, [2-14C]- and [3-14C]alanine were used as substrates in parallel. About 40% of the alanine carbon removed was recovered as CO2 and oxidation of C1 of alanine accounted for most of the CO2 released from alanine. Calculations reveal that the ATP produced exceeded 3.2-fold the ATP consumed in relation to alanine metabolism. It is concluded that, in human kidney, alanine may serve as an energy supplier and as a precursor of glucose and ammonia.

A simple model for alanine metabolism in isolated rat hepatocytes

A simple model describing reactions of alanine metabolism in isolated hepatocytes from fasted rats is proposed and applied to radioactive data obtained in experiments in which L-[1-14C]-, L-[2-14C]-, L-[3-14C]-, and L-[U-14C]alanine as well as L-alanine plus NaH14CO3 were used as substrates in parallel. Measurements of the rates of incorporation of the label into glucose and CO2 and of accumulation of [1-14C]pyruvate, [1-14C]lactate, [1-14C]alanine and [1-14C]glutamate plus [1-14C]glutamine from the different substrates used allows to calculate flux of alanine carbon through the various metabolic steps taken into account in the model. The validity of this model is indicated by the agreement found between calculations and measurement of the 14CO2 released from [1-14C]alanine as well as between the values of flux through pyruvate carboxylase calculated in two different ways. It is shown that the oxaloacetate synthesized by pyruvate carboxylase enters into the Krebs cycle and into the pathway of phosphoenolpyruvate synthesis in about equal proportions and that about 40% of the oxaloacetate synthesized as a result of alanine metabolism is derived from the Krebs cycle operation. These results, together with the conclusion that flux of alanine carbon through pyruvate dehydrogenase is negligible, are in agreement with known characteristics of hepatic alanine metabolism in the fasted state and, therefore, provide further evidence for the validity of the model proposed in the present study.