Tissue Resistance during Large-Volume Injections in Subcutaneous Tissue of Minipigs

Customized Heparinized Alginate and Collagen Hydrogels for Tunable, Local Delivery of Angiogenic Proteins

Therapeutic protein delivery has ushered in a promising new generation of disease treatment, garnering more recognition for its clinical potential than ever. However, proteins' limited stability, extremely short average half-lives, and evidenced toxicity following systemic delivery continue to undercut their efficacy. Biomaterial-based protein delivery, however, demonstrates the potential to overcome these obstacles. To this end, we have developed a heparinized alginate and collagen hydrogel for the local, sustained delivery of therapeutic proteins. In an effort to match this ubiquitous application of protein delivery to various disease states and target tissues with sufficient versatility, we identified three distinct delivery modes as design targets. A shear-thinning, low-viscosity injectable for minimal tissue damage, a higher-viscosity gel plug for subcutaneous injection, and a submillimeter-thickness film for solid-form implantation were optimized and characterized in this work. In vitro assessments confirmed feasible injection control, mechanical stability for up to 6 h of unsubmerged storage, and isotropic early collagen fibril assembly. Release kinetics were assessed both in vitro and in vivo, demonstrating up to 14 days of functional vascular endothelial growth factor delivery. Rodent models of pulmonary hypertension, subcutaneous injection, and myocardial infarction, three promising applications of protein therapeutics, were used to assess the feasible delivery and biocompatibility of the injectable gel, gel plug, and film, respectively. Histological evaluation of the delivered materials and surrounding tissue showed high biocompatibility with cell and blood vessel infiltration, remodeling, and integration with the host tissue. Our successful customization of the biomaterial to heterogeneous delivery modes demonstrates its versatile capacity for the local, sustained delivery of therapeutic proteins for a diverse array of regenerative medicine applications.

Visualisation and quantification of subcutaneous injections of different volumes, viscosities and injection rates: An ex-vivo micro-CT study

The effects of subcutaneous (SC) injection parameters such as drug formulation volume, viscosity and injection rate on therapeutic performance and tolerability have not been established for any drug product. In this study four groups of SC injections were performed on fresh ex vivo minipig abdominal tissue samples, varying volume (0.5-1 mL), viscosity (1-11 cP) and rate (0.02-0.1 mL/s). Micro-CT provided high resolution (50 micron) imaging of the SC tissues before and after injection, enabling a detailed 3D visualisation and analysis of how both injection parameters and tissue microstructure influence spatial distribution of injectables. We found that volume was the only significant factor for spatial distribution of injectate within our design space, and there were no significant factors for tissue backpressure. Variability within test groups was typically greater than differences between group means. Accordingly, whilst the higher viscosity formulations consistently exhibited reduced spatial distribution, the sample size was not large enough to establish confidence in this result. Comparing our findings to clinical evidence, we conclude that injection site and depth are more likely to influence PK and bioavailability than volume, viscosity and rate within our experimental space.

Understanding the interaction forces between shield-triggered autoinjectors and skin: an in-depth noninvasive study

OBJECTIVE

This noninvasive study aimed to understand the interaction between shield-triggered autoinjectors (AI) and skin at the point of activation, hypothesizing that the AI's housing absorbs a significant amount of the user-applied force depending on shield design and skin characteristics.

METHODS

Twenty-seven volunteers used a test device measuring applied force versus shield force and indentation depth relative to shield length (2,4,6,8 mm) in standing and sitting positions.

RESULTS

Significant differences were found between applied and shield force for the different shield lengths. Shorter shields resulted in significantly lower force transfer coefficients, with means ranging from 0.72 for the 2 mm shield to 0.94 for the 8 mm shield. ANOVA revealed statistically significant factors (p < .05), including position and gender, with females generally having lower coefficient values. Indentation depth increased with higher forces and varied significantly between positions without significant shield length impact.

CONCLUSION

The findings confirm that an increase in shield length at the point of activation reduces skin friction with the housing, resulting in less force loss and a lower device activation force perceived by the user. Force loss can be further reduced by standing up. Understanding device-tissue interactions will support development of better AIs with fewer user failures.

Enabling faster subcutaneous delivery of larger volume, high viscosity fluids

OBJECTIVES

Many current subcutaneous (SC) biologic therapies may require >1 mL volume or have increased viscosity, necessitating new delivery system approaches. This study evaluated 2-mL large-volume autoinjector (LVAI) delivery performance across varying solution viscosities and design inputs to assess the design space and identify configurations that produce practical injection times.

METHODS

Investigational LVAI delivery duration and volume, depot location, and tissue effects were examined in both air and in vivo models across various pre-filled syringe (PFS) cannula types (27 G Ultra-thin wall [UTW], 27 G special thin wall [STW], or 29 G thin-wall [TW]), drive spring forces (SF_LOW or SF_HIGH), and Newtonian solutions (2.3-50 centipoise [cP]).

RESULTS

Within each design configuration, increasing PFS internal diameters and spring forces reduced delivery times, while increasing viscosity increased times. The 27 G UTW PFS/SF_HIGH combination achieved shorter delivery times across all injection conditions, with 2 mL in vivo durations <15 seconds at ≤31 cP and routinely <20 seconds at 39 and 51 cP, with nominal and transitory tissue effects.

CONCLUSION

PFS cannula and spring force combinations can be tailored to achieve various injection durations across viscosities, while UTW PFS enables faster rates to potentially better accommodate human factors during LVAI injection, especially at high viscosity.

Body-Powered and Portable Soft Hydraulic Actuators as Prosthetic Hands

Soft robotic actuators are highly flexible, compliant, dexterous, and lightweight alternatives that can potentially replace conventional rigid actuators in various human-centric applications. This research aims to develop a soft robotic actuator that leverages body movements to mimic the function of human fingers for gripping and grasping tasks. Unlike the predominantly used chamber-based actuation, this study utilizes actuators made from elastomers embedded with fiber braiding. The Young’s modulus of the elastomer and braiding angles of the fiber highly influenced the bending angle and force generated by these actuators. In this experiment, the bending and force profiles of these actuators were characterized by varying the combinations of elastomeric materials and braiding angles to suit hand manipulation tasks. Additionally, we found that utilizing water, which is relatively more incompressible than air, as the actuation fluid enabled easier actuation of the actuators using body movements. Lastly, we demonstrated a body-powered actuator setup that can provide comfort to patients in terms of portability, standalone capability, and cost effectiveness, potentially allowing them to be used in a wide range of wearable robotic applications.

Intraocular pressure and injection forces during intravitreal injection into enucleated porcine eyes

Injection of biological molecules into the intravitreous humor is of increasing interest for the treatment of posterior segment eye diseases such as age-related degenerative macular degeneration. The injection volume is limited by an increase in intraocular pressure (IOP) and 50-100 µL are typically used for most intravitreally (IVT) applied commercial products. Direct measurement of IOP is difficult and has not been studied dependent on solution properties and injection rates. We used an instrumental set-up to study IOP ex vivo using healthy enucleated porcine eyes. IOP was determined as a function of injection volume for viscosities between 1 and 100 mPas, injection rates of 0.1, 1, and 1.5 mL/min, and needle length and diameter (27/30G and 0.5/0.75″) using Dextran solutions. IOP increased exponentially for injection volumes larger than 100 µL. We did not observe differences in IOP dependent on viscosity, injection rate, and needle diameter. However, variability increased significantly for injection volumes larger than 100 µL and, unexpectedly, declined with higher viscosities. We demonstrate that the exponential increase in IOP is not reflected by injection force measurements for typical configurations that are used for IVT application. The present findings may guide injection volumes for intravitreal injection and inform injection force considerations during technical drug product development.

Opportunities in an Evolving Pharmaceutical Development Landscape: Product Differentiation of Biopharmaceutical Drug Products

The current perspective reviews the biopharmaceutical market until end of 2020 and highlights the transforming biopharmaceutical landscape during the recent decade. In particular, the rise of biosimilars and the development of new therapeutic modalities through recent advancement in molecular biology research sustainably change the product scenery. The present manuscript describes opportunities for pharmaceutical technical development, highlighting concepts such as product differentiation to succeed in a competitive product landscape. Product differentiation offers the opportunity for numerous life-cycle options and market exclusivity through incremental improvements in standard of care treatment. In particular, different formulation options and formulation-device combinations are described, focusing on systemic delivery of monoclonal antibody products and patient-centered development. The concept of product differentiation is exemplified in a case study about HER2+ breast cancer therapy, underlining pharmaceutical technical solutions and major improvements for the patient.