Biology subjects

Knox, S. M.

Publications and source records attributed to Knox, S. M..

5 recordsLinked to original sources

bioRxiv2022

Long-term functional regeneration of radiation damaged salivary glands through delivery of a neurogenic hydrogel

Salivary gland acinar cells are severely depleted after radiotherapy for head and neck cancer, leading to loss of saliva and extensive oro-digestive complications. With no regenerative therapies available, organ dysfunction is irreversible. Here using the adult murine system, we demonstrate radiation-damaged salivary glands can be functionally regenerated via sustained delivery of the neurogenic muscarinic receptor agonist, cevimeline. We show that endogenous gland repair coincides with increased nerve activity and acinar cell division that is limited to the first week post-radiation, with extensive acinar cell degeneration, dysfunction and cholinergic denervation occurring thereafter. However, we discovered that mimicking cholinergic muscarinic input via sustained local delivery of a cevimeline-alginate hydrogel was sufficient to regenerate innervated acini and retain physiological saliva secretion at non-irradiated levels over the long-term (> 3 months). Thus, we reveal a novel regenerative approach for restoring epithelial organ structure and function that has significant implications for human patients. TeaserNovel application of an injectable neurogenic-based hydrogel for restoring the structure and function of radiation-damaged tissue.

cell biology↗

bioRxiv2022

A synthetic tear protein resolves dry eye through promoting corneal nerve regeneration.

Corneal architecture is essential for vision and is greatly perturbed by the absence of tears due to the highly prevalent disorder dry eye. With no regenerative therapies available, pathological alterations of the ocular surface in response to dryness, including persistent epithelial defects and poor wound healing, result in lifelong morbidity. Here, using a mouse model of aqueous-deficient dry eye, we reveal that topical application of the synthetic tear protein lacripep reverses the pathological outcomes of dry eye through restoring the extensive network of corneal nerves that are essential for tear secretion, barrier function, epithelial homeostasis and wound healing. Intriguingly, the restorative effects of lacripep occur despite extensive immune cell infiltration, suggesting tissue reinnervation and regeneration can be achieved under chronic inflammatory conditions. In summary, our data highlight lacripep as a first-in-class regenerative therapy for returning the cornea to a near homeostatic state in individuals who suffer from dry eye. TeaserTopical application of a synthetic tear protein repairs dry eye-mediated corneal damage through driving functional sensory reinnervation.

cell biology↗

bioRxiv2022

Single-Cell Multi-Omic Roadmap of Human Fetal Pancreatic Development

The critical cellular transitions that govern human pancreas development are largely unknown. We performed large-scale single-cell RNA-sequencing (scRNA-Seq) to interrogate human fetal pancreas development from 8-20 weeks post conception. We identified 103 distinct cell types, including four novel endocrine progenitor subtypes displaying unique transcriptional features and differentiation potency. Integration with single-nucleus Assay for Transposase Accessible Chromatin Sequencing (snATAC-Seq) identified candidate regulators of human endocrine cell fate and revealed development-specific regulatory annotation at diabetes risk loci. Comparison of in vitro stem cell-derived and endogenous endocrine cells predicted aberrant genetic programs leading to the generation of off-target cells. Finally, knock-out studies revealed that the gene FEV regulates human endocrine differentiation. This work establishes a roadmap of human pancreatic development, highlights previously unappreciated cellular diversity and lineage dynamics, and provides a blueprint for understanding pancreatic disease and physiology, as well as generating human stem cell-derived islet cells in vitro for regenerative medicine purposes.

developmental biology↗

bioRxiv2020

Functional specialization of human salivary glands and origins of proteins intrinsic to human saliva

Salivary proteins are essential for maintaining health in the oral cavity and proximal digestive tract and serve as a diagnostic window into human disease. However, their precise organ origins remain unclear. Through transcriptomic analysis of major adult and fetal salivary glands, and integration with the saliva proteome and transcriptomes of 28+ organs, we linked human saliva proteins to their source, identified salivary gland-specific genes, and uncovered fetal- and adult-specific gene repertoires. Our results also provide new insights into the degree of gene retention during maturation and suggest that functional diversity between adult gland-types is driven by specific dosage combinations of hundreds of transcriptional regulators rather than a few gland-specific factors. Finally, we demonstrate the hitherto unrecognized heterogeneity of the human acinar cell lineage. Our results pave the way for future investigations into glandular biology and pathology, as well as salivas use as a diagnostic fluid.

developmental biology↗

bioRxiv2018

Diverse progenitor cells preserve salivary gland ductal architecture after radiation induced damage

The ductal system of the salivary gland has long been postulated to be resistant to radiation-induced damage, a common outcome incurred by head and neck cancer patients receiving radiotherapy. Yet, whether the ducts are capable of regenerating after genotoxic injury, or if damage to ductal cells induces lineage plasticity, as has been reported in other organ systems, remains unknown. Here, we show that two ductal progenitor populations marked by KRT14 and KIT exclusively maintain non-overlapping ductal compartments after radiation exposure but do so through distinct cellular mechanisms. KRT14+ progenitor cells are fast cycling cells that proliferate in response to radiation-induced damage in a sustained manner and divide asymmetrically to produce differentiated cells of the larger granulated ducts. Conversely, KIT+ cells are long lived progenitors for the intercalated ducts that undergo few cell divisions either during homeostasis or after gamma radiation, thus maintaining ductal architecture in the near absence of cell turnover. Together, these data illustrate the regenerative capacity of the salivary ducts and highlight the heterogeneity in the damage responses used by salivary progenitor cells to maintain tissue architecture.\n\nSummary StatementThe salivary gland ductal network is maintained during homeostasis and after genotoxic injury by diverse progenitors that respond differentially to radiation induced damage.

developmental biology↗