Understanding the Role of Biofilms in Acute Recurrent Tonsillitis through 3D Bioprinting of a Novel Gelatin-PEGDA Hydrogel.

Acute recurrent tonsillitis is a chronic, biofilm-related infection that is a significant burden to patients and healthcare systems. It is often treated with repeated courses of antibiotics, which contributes to antimicrobial resistance. Studying biofilms is key to understanding this disease. In vitro modelling using 3D bioprinted hydrogels is a promising approach to achieve this. A novel gelatin-PEGDA pseudomonas fluorescens-laden bioink was developed and bioprinted in a 3D hydrogel construct fabricated using computer-aided design to mimic the tonsillar biofilm environment. The bioprinted constructs were cultured at 37 °C in lysogeny broth for 12 days. Bacterial growth was assessed by spectrophotometry. Cellular viability analysis was conducted using optical fluorescence microscopy (FDA/PI staining). A biocompatible 3D-printed bacteria-laden hydrogel construct was successfully fabricated. Bacterial growth was observed using optical fluorescence microscopy. A live/dead cellular-staining protocol demonstrated bacterial viability. Results obtained after the 12-day culture period showed higher bacterial growth in the 1% gelatin concentration construct compared to the 0% control. This study demonstrates the first use of a bacteria-laden gelatin-PEGDA hydrogel for biofabrication of a 3D-printed construct designed to model acute recurrent tonsillitis. Initiating a study with clinically relevant ex vivo tonsil bacteria will be an important next step in improving treatment of this impactful but understudied disease.

Evaluation of novel urinary renal biomarkers: biological variation and reference change values.

A number of novel urinary biomarkers have been identified and partially qualified for use as markers for renal injury in rats. We used two multiplex assays for these novel biomarkers to quantify biomarker concentration in serial urine collections from rats of both sexes administered varying concentrations of cisplatin. From these data, we calculate inter-individual variation and reference ranges from predose animals and intra-individual variation and reference change values from undosed control animals. The biomarkers evaluated are albumin, α glutathione s-transferase, glutathione S-transferase-yb1, lipocalin-2, kidney injury molecule-1, osteopontin, and renal papillary antigen 1. For any creatinine-corrected novel biomarkers, we found intra-individual variation to be no greater than 44% and inter-individual variation to be no greater than 46%. Reference change values for most corrected analytes (except osteopontin) were 50-100%, indicating that a >100% increase in analyte concentration between serial samples would be unlikely to be associated with inherent analytical or biological variation.

Evaluation of novel urinary renal biomarkers with a cisplatin model of kidney injury: effects of collection period.

A number of novel urinary biomarkers have been identified and partially qualified for use as markers for renal injury in rats. To date, all evaluation studies have been made using 18 to 24 hour collection periods. However, shorter, more welfare friendly, urine collection periods are also used in industry. In this article, we quantify urinary biomarker concentration in serial paired sequential short and long urine collections from male rats administered varying concentrations of cisplatin. We calculate the rate of biomarker excretion in normal animals for both collection periods and the bias and correlation in urinary biomarker concentration between collection periods in dosed and control animals, and we estimate the level of agreement in biomarker concentration between both collection periods. We conclude that although there are minor differences in the concentration of some urinary biomarkers that are dependent upon the time and duration of collection, shorter collection protocols do not influence subsequent interpretation of normalized urinary biomarker data for most biomarkers.