Leveraging Mechanical Forces to Target Insulin Injection-Induced Lipohypertrophy and Fibrosis

Development and validation of a distress measurement for insulin injections among patients with diabetes

Insulin injections are stressful but necessary for people with diabetes. This study aimed to develop and validate the Distress of Self-Injection (DSI) scale for patients with diabetes aged ≥ 10 years. We created a questionnaire to evaluate DSI after examining each item following a literature review. The DSI scale with 20 questions in three domains (physical [4], psychosocial [7], and process [9]) was developed and tested at the Samsung Medical Center in Seoul, Korea, from April to September 2021. To verify structural validity, exploratory and confirmatory factor analyses (CFA) were conducted. Internal consistency was also calculated. To assess construct and criterion validity, the correlation between the DSI scale and Korean version of the Problem Areas in Diabetes (PAID-K) scale was obtained. Cronbach's alpha varied from 0.69 to 0.87, and the DSI score was 0.90, demonstrating acceptable internal consistency. CFA fit indices (CFI = 0.980; RMSEA = 0.033) were favorable. DSI and pertinent PAID-K domains correlated strongly. For measuring self-injection distress, the DSI score had good accuracy. For patients with diabetes aged ≥ 10 years who self-inject insulin, the DSI was a viable and accurate method for quantifying discomfort associated with insulin injection. Health practitioners should use the DSI to communicate with patients about their suffering.

Investigation of macromolecular transport through tunable collagen hyaluronic acid matrices

Therapeutic macromolecules possess properties such as size and electrostatic charge that will dictate their transport through subcutaneous (SC) tissue and ultimate bioavailability and efficacy. To improve therapeutic design, platforms that systematically measure the transport of macromolecules as a function of both drug and tissue properties are needed. We utilize a Transwell chamber with tunable collagen-hyaluronic acid (ColHA) hydrogels as an in vitro model to determine mass transport of macromolecules using non-invasive UV spectroscopy. Increasing hyaluronic acid (HA) concentration from 0 to 2 mg/mL within collagen gels decreases the mass transport of five macromolecules independent of size and charge and results in a maximum decrease in recovery of 23.3% in the case of bovine immunoglobulin G (IgG). However, in a pure 10 mg/mL HA solution, negatively-charged macromolecules bovine serum albumin (BSA), β-lactoglobulin (BLg), dextran (Dex), and IgG had drastically increased recovery by 20-40% compared to their performance in ColHA matrices. This result was different from the positively-charged macromolecule Lysozyme (Lys), which, despite its small size, showed reduced recovery by 3% in pure HA. These results demonstrate two distinct regimes of mass transport within our tissue model. In the presence of both collagen and HA, increasing HA concentrations decrease mass transport; however, in the absence of collagen, the high negative charge of HA sequesters and increases residence time of positively-charged macromolecules and decreases residence time of negatively-charged macromolecules. Through our approach, ColHA hydrogels serve as a platform for the systematic evaluation of therapeutic macromolecule transport as a function of molecular characteristics.