Biology subjects

Bottino, R.

Publications and source records attributed to Bottino, R..

11 recordsLinked to original sources

bioRxiv2025

Scalable 3D Bioprinting of Human Islets in a Pancreatic Decellularized Extracellular Matrix-Enriched Bioink for Beta-Cell Replacement Therapy

Allogeneic cell transplantation such as beta-cell replacement for treatment of type 1 diabetes (T1D) is constrained by poor graft survival and functionality, immune rejection, and the lack of scalable biomanufacturing processes. Here, we engineered functional human islet constructs that replicate the physiomimetic human pancreatic microenvironment by employing a clinically-scalable 3D bioprinting system. To support human islet viability and function, we developed alginate-based bioinks incorporating human pancreatic decellularized extracellular matrix (dECM). These bioink formulations were optimized for shear-thinning properties for extrusion of human islets, as well as selective permeability that supports nutrient and therapeutic molecule exchange. Extrusion-based printing parameters were refined to minimize shear stress-induced damage to human islets. The resulting bioprinted pancreatic constructs demonstrated robust structural integrity, high human islet viability (>85%), and long-term glucose-stimulated insulin secretion (GSIS) over a 21-days in vitro culture period, even at a high islet packing density (10,000 islet equivalent/mL) while free islet controls displayed a significant functional decline. The higher performance of bioprinted islets maybe attributable to the supportive 3D dECM-rich microenvironment mitigating culture-induced stress by recapitulating the islet pancreatic niche. This scalable 3D dECM-alginate bioprinted platform represents a new advanced functional material for advancing clinically translatable bio-artificial pancreas therapies for T1D.

bioengineering↗

bioRxiv2025

Engineering sialylation in pigs: A promising strategy for overcoming xenograft rejection and revolutionizing organ transplantation.

The organ shortage crisis leaves over 100,000 people waiting for transplants, causing 6,000 deaths annually. To address this, pigs are being explored as potential donors. Despite advances like the FDA-approved GalSafe pig, immunological challenges remain. Key issues include strong antibody, innate, and cellular immune responses, along with coagulation problems due to differences in glycosides and sialic acid linkages, which prevent long-term xenograft survival. Hyperacute rejection, caused by instant blood-mediated immune reaction (IBMIR), is a persistent problem, characterized by inflammatory and thrombotic responses when, for example, xenogeneic islets contact blood or reperfusion post anastomosis of transplanted organ. To overcome IBMIR, and other innate immune mediated rejection, we expressed human sialyltransferase (ST8Sia6) in otherwise wild type, porcine endothelium, creating human-like sialic linkages on porcine glycoproteins and lipids. This increased expression of human sialic acid 2,8- linkage on porcine endothelial cells, enhanced sialic-acid-binding immunoglobulin-like lectin (Siglec) binding reducing immune effector mechanisms such as complement activation and cell cytotoxicity. It also correlated with reduced CTL-targeted killing, lower levels of CD107a, perforin, and IFN-{gamma} production. This coincided with higher immunoreceptor tyrosine-based inhibition motif (ITIM) induction, mirroring immune tolerance seen in fetal development and tumor immune evasion. Moreover, the landscape of the expression induced transcriptome of ST8Sia6, overexpression in porcine kidney cells revealed differential expression of genes involved in immune downregulation, cell signaling, and metabolic alteration. Expression of 2,8-linked disialic acids on porcine cells protected against immune effector mechanisms, reducing complement activation, immune cell activation, and CTL killing. These findings suggest that enhanced 2,8- linked disialic acid expression can modulate the innate and adaptive immune response, reducing xenograft rejection. This approach may improve xenotransplantation success, mitigate primary non-function in xenografts, and be applied to human iPSC-derived islets and other cell products. Further research into the specific mechanisms of these immunomodulatory effects could guide the development of effective strategies for xenotransplantation.

immunology↗

bioRxiv2024

Mapping histological and functional maturation of human endocrine pancreas across early postnatal periods

Human endocrine cell differentiation and islet morphogenesis play critical roles in determining islet cell mass and function, but the events and timeline of these processes are incompletely defined. To better understand early human islet cell development and maturation, we collected 115 pediatric pancreata and mapped morphological and spatiotemporal changes from birth through the first ten years of life. Using quantitative analyses and a combination of complementary tissue imaging approaches, including confocal microscopy and whole-slide imaging, we developed an integrated model for endocrine cell formation and islet architecture, including endocrine cell type heterogeneity and abundance, endocrine cell proliferation, and islet vascularization and innervation. We also assessed insulin and glucagon secretory profiles in isolated islet preparations from pediatric donors aged 2 months to 10 years and found a temporal difference in the maturation of insulin secretion compared to glucagon secretion. This comprehensive summary of postnatal and pediatric pancreatic islet development provides a framework for future studies and integration of emerging genetic and genomic data related to islet biology and diabetes risk.

developmental biology↗

bioRxiv2021

RFX6-mediated dysregulation defines human β cell dysfunction in early type 2 diabetes

A hallmark of type 2 diabetes (T2D), a major cause of world-wide morbidity and mortality, is dysfunction of insulin-producing pancreatic islet {beta} cells1-3. T2D genome-wide association studies (GWAS) have identified hundreds of signals, mostly in the non-coding genome and overlapping {beta} cell regulatory elements, but translating these into biological mechanisms has been challenging4-6. To identify early disease-driving events, we performed single cell spatial proteomics, sorted cell transcriptomics, and assessed islet physiology on pancreatic tissue from short-duration T2D and control donors. Here, through integrative analyses of these diverse modalities, we show that multiple gene regulatory modules are associated with early-stage T2D {beta} cell-intrinsic defects. One notable example is the transcription factor RFX6, which we show is a highly connected {beta} cell hub gene that is reduced in T2D and governs a gene regulatory network associated with insulin secretion defects and T2D GWAS variants. We validated the critical role of RFX6 in {beta} cells through direct perturbation in primary human islets followed by physiological and single nucleus multiome profiling, which showed reduced dynamic insulin secretion and large-scale changes in the {beta} cell transcriptome and chromatin accessibility landscape. Understanding the molecular mechanisms of complex, systemic diseases necessitates integration of signals from multiple molecules, cells, organs, and individuals and thus we anticipate this approach will be a useful template to identify and validate key regulatory networks and master hub genes for other diseases or traits with GWAS data.

cell biology↗

bioRxiv2021

Combinatorial transcription factor profiles predict mature and functional human islet α and β cells

Islet-enriched transcription factors (TFs) exert broad control over cellular processes in pancreatic and {beta} cells and changes in their expression are associated with developmental state and diabetes. However, the implications of heterogeneity in TF expression across islet cell populations are not well understood. To define this TF heterogeneity and its consequences for cellular function, we profiled >40,000 cells from normal human islets by scRNA-seq and stratified and {beta} cells based on combinatorial TF expression. Subpopulations of islet cells co-expressing ARX/MAFB ( cells) and MAFA/MAFB ({beta} cells) exhibited greater expression of key genes related to glucose sensing and hormone secretion relative to subpopulations expressing only one or neither TF. Moreover, all subpopulations were identified in native pancreatic tissue from multiple donors. By Patch-seq, MAFA/MAFB co-expressing {beta} cells showed enhanced electrophysiological activity. Thus, these results indicate combinatorial TF expression in islet and {beta} cells predicts highly functional, mature subpopulations.

genomics↗

bioRxiv2020

Bromodomain protein inhibition protects β-cells from cytokine-induced death and dysfunction via antagonism of NF-κB pathway.

Cytokine induced {beta}-cell apoptosis is the major pathogenic mechanism in type 1 diabetes (T1D). Despite significant advances in understanding underlying mechanisms, few drugs have been translated to protect {beta}-cells in T1D. Epigenetic modulators such as bromodomain-containing BET (Bromo- and Extra-Terminal) proteins are important regulators of immune responses. Pre-clinical studies have demonstrated a protective effect of BET inhibitors in NOD (non-obese diabetes) mouse model of T1D. However, the role of BET proteins in {beta}-cell function in response to cytokines is unknown. Here we demonstrate that I-BET, a BET protein inhibitor, protected {beta}-cells from cytokine induced dysfunction and death. In vivo administration of I-BET to mice exposed to low-dose STZ (streptozotocin), a model of T1D, significantly reduced {beta}-cell apoptosis and preserved {beta}-cell mass, suggesting a cytoprotective function of I-BET. Furthermore, human islets treated with I-BET displayed better glucose stimulated insulin secretion compared to controls, when exposed to cytokines. Mechanistically, RNA-Seq analysis revealed I-BET treatment suppressed pathways involved in apoptosis, including NF-kB signaling, while maintaining the expression of genes critical for {beta}-cell function, such as Pdx1 and Ins1. Taken together, this study demonstrates that I-BET is effective in protecting {beta}-cells from cytokine-induced dysfunction and apoptosis, and may have potential therapeutic values in T1D.

molecular biology↗

bioRxiv2020

Tead1 reciprocally regulates adult β-cell proliferation and function

Proliferative quiescence in {beta}-cells is required to maintain functional competence. While this presents a significant hurdle in regenerative therapy for diabetes, the molecular underpinnings of this reciprocal relationship remain unclear. Here, we demonstrate that TEAD1, the transcription effector of the mammalian-Hippo pathway, drives developmental stage-specific {beta}-cell proliferative capacity in conjunction with its functional maturation. TEAD1 promotes adult {beta}-cell mature identity by direct transcriptional control of a network of critical {beta}-cell transcription factors, including, Pdx1, Nkx6.1, and MafA, while its regulation of Cdkn2a maintains proliferative quiescence. Consequently, mice with either constitutive or inducible genetic deletion of TEAD1 in {beta}-cells developed overt diabetes due to a severe loss of secretory function despite induction of proliferation. Furthermore, we show that TEAD1 has a similar regulatory role in human {beta}-cells. Consistent with this function in {beta}-cells, variants in TEAD1 have been associated with c-HOMA-B in American Indians. We propose that TEAD1 is an essential intrinsic molecular switch coordinating adult {beta}-cell proliferative quiescence with mature identity and its differential modulation may be necessary to overcome the challenge of inducing proliferation with functional competence in human beta cells.

molecular biology↗

bioRxiv2019

Human pseudoislet system enables detection of differences in G-protein-coupled-receptor signaling pathways between α and β cells

G-protein-coupled-receptors (GPCRs) modulate insulin secretion from {beta} cells and glucagon secretion from cells. Here, we developed an integrated approach to study the function of primary human islet cells using genetically modified pseudoislets that resemble native islets across multiple parameters. We studied the Gi and Gq GPCR pathways by expressing the designer receptors exclusively activated by designer drugs (DREADDs) hM4Di or hM3Dq. Activation of Gi signaling reduced insulin and glucagon secretion, while activation of Gq signaling stimulated glucagon secretion but had both stimulatory and inhibitory effects on insulin secretion. Further, we developed a microperifusion system that allowed synchronous acquisition of GCaMP6f biosensor signal and hormone secretory profiles and showed that the dual effects for Gq signaling occur through changes in intracellular Ca2+. By combining pseudoislets with a microfluidic system, we co-registered intracellular signaling dynamics and hormone secretion and demonstrated differences in GPCR signaling pathways between human {beta} and cells.

cell biology↗

bioRxiv2019

Single nucleus RNA sequencing maps acinar cell states in a human pancreas cell atlas

Molecular evidence of cellular heterogeneity in the human exocrine pancreas has not been established, due to the local concentration of hydrolytic enzymes that can rapidly degrade cells and RNA upon resection. Here we innovated single-nucleus RNA sequencing protocols, and profiled more than 120,000 cells from adult and neonatal human donors to create the first comprehensive atlas of human pancreas cells, including epithelial and non-epithelial constituents. Adult and neonatal pancreata shared common features, including the presence of previously undetected acinar subtypes, but also showed marked differences in the composition of the endocrine, endothelial, and immune compartments. Spatial cartography, including cell proximity mapping through in situ sequencing, revealed dynamic developmental cell topographies in the endocrine and exocrine pancreas. Our human pancreas cell atlas can be interrogated to understand pancreatic cell biology, and provides a crucial reference set for future comparisons with diseased tissue samples to map the cellular foundations of pancreatic diseases.

genomics↗

bioRxiv2019

Molecular and genetic regulation of pig pancreatic islet cell development

Reliance on rodents for understanding pancreatic genetics, development and islet function could limit progress in developing interventions for human diseases like diabetes mellitus. Similarities of pancreas morphology and function suggest that porcine and human pancreas developmental biology may have useful homologies. However, little is known about pig pancreas development. To fill this knowledge gap, we investigated fetal and neonatal pig pancreas at multiple, crucial developmental stages using modern experimental approaches. Purification of islet {beta}-, - and {delta}-cells followed by transcriptome analysis (RNA-Seq) and immunohistology identified cell- and stage-specific regulation, and revealed that pig and human islet cells share characteristic features not observed in mice. Morphometric analysis also revealed endocrine cell allocation and architectural similarities between pig and human islets. Our analysis unveiled scores of signaling pathways linked to native islet {beta}-cell functional maturation, including evidence of fetal -cell GLP-1 production and signaling to {beta}-cells. Thus, the findings and resources detailed here show how pig pancreatic islet studies complement other systems for understanding the developmental programs that generate functional islet cells, and that are relevant to human pancreatic diseases. Summary StatementThis study reveals transcriptional, signaling and cellular programs governing pig pancreatic islet development, including striking similarities to human islet ontogeny, providing a novel resource for advancing human islet replacement strategies.

developmental biology↗

bioRxiv2017

Single cell transcriptome analysis of human pancreas reveals transcriptional signatures of aging and somatic mutation patterns.

As organisms age, cells accumulate genetic and epigenetic changes that eventually lead to impaired organ function or catastrophic transformation such as cancer. Since aging appears to be a stochastic process of increasing disorder1 cells in an organ will be individually affected in different ways - thus rendering bulk analyses of postmitotic adult tissues difficult to characterize. Here we directly measure the effects of aging in primary human tissue by performing single-cell transcriptome analysis of 2544 human pancreas cells from eight donors spanning six decades of life. We find that islet cells from older donors have increased levels of molecular disorder as measured both by noise in the transcriptome and by the number of cells which display inappropriate hormone expression, revealing a transcriptional instability associated with aging. By further analyzing the spectrum of somatic mutations in single cells, we found a specific age-dependent mutational signature characterized by C to A and C to G transversions. These mutations are indicators of oxidative stress and the signature is absent in single cells from human brain tissue or in a tumor cell line. We have used the single cell measurements of transcriptional noise and mutation level to identify molecular pathways correlated with these changes that could influence human disease. Our results demonstrate the feasibility of using single-cell RNA-seq data from primary cells to derive meaningful insights into the genetic processes that operate on aging human tissue and to determine molecular mechanisms coordinated with these processes.

genomics↗