Biology subjects

Kamalakar, A.

Publications and source records attributed to Kamalakar, A..

4 recordsLinked to original sources

bioRxiv2023

Harnessing Bilayer Biomaterial Delivery of FTY720 as an Immunotherapy to Accelerate Oral Wound Healing

Orofacial clefts are the most common craniofacial congenital anomaly. Following cleft palate repair, up to 60% of surgeries have wound healing complications leading to oronasal fistula (ONF), a persistent connection between the roof of the mouth and the nasal cavity. The current gold standard methods for ONF repair use human allograft tissues; however, these procedures have risks of graft infection and/or rejection, requiring surgical revisions. Immunoregenerative therapies present a novel alternative approach to harness the bodys immune response and enhance the wound healing environment. We utilized a repurposed FDA-approved immunomodulatory drug, FTY720, to reduce the egress of lymphocytes and induce immune cell fate switching toward pro-regenerative phenotypes. Here, we engineered a bilayer biomaterial system using Tegaderm, a liquid-impermeable wound dressing, to secure and control the delivery of FTY720- nanofiber scaffolds (FTY720-NF). We optimized release kinetics of the bilayer FTY720-NF to sustain drug release for up to 7d with safe, efficacious transdermal absorption and tissue biodistribution. Through comprehensive immunophenotyping, our results illustrate a pseudotime pro-regenerative state transition in recruited hybrid immune cells to the wound site. Additional histological assessments established a significant difference in full thickness ONF closure in mice on Day 7 following treatment with bilayer FTY720-NF, compared to controls. These findings demonstrate the utility of immunomodulatory strategies for oral wound healing, better positing the field to develop more efficacious treatment options for pediatric patients. One Sentence SummaryLocal delivery of bilayer FTY720-nanofiber scaffolds in an ONF mouse model promotes complete wound closure through modulation of pro-regenerative immune and stromal cells.

bioengineering↗

bioRxiv2023

Delivery of A Jagged1-PEG-MAL hydrogel with Pediatric Human Bone Cells Regenerates Critically-Sized Craniofacial Bone Defects

Treatments for congenital and acquired craniofacial (CF) bone abnormalities are limited and expensive. Current reconstructive methods include surgical correction of injuries, short-term bone stabilization, and long-term use of bone grafting solutions, including implantation of (i) allografts which are prone to implant failure or infection, (ii) autografts which are limited in supply. Current bone regenerative approaches have consistently relied on BMP2 application with or without addition of stem cells. BMP2 treatment can lead to severe bony overgrowth or uncontrolled inflammation, which can accelerate further bone loss. Bone marrow-derived mesenchymal stem cell-based treatments, which do not have the side effects of BMP2, are not currently FDA approved, and are time and resource intensive. There is a critical need for novel bone regenerative therapies to treat CF bone loss that have minimal side effects, are easily available, and are affordable. In this study we investigated novel bone regenerative therapies downstream of JAGGED1 (JAG1). We previously demonstrated that JAG1 induces murine cranial neural crest (CNC) cells towards osteoblast commitment via a NOTCH non-canonical pathway involving JAK2-STAT5 (1) and that JAG1 delivery with CNC cells elicits bone regeneration in vivo. In this study, we hypothesize that delivery of JAG1 and induction of its downstream NOTCH non-canonical signaling in pediatric human osteoblasts constitute an effective bone regenerative treatment in an in vivo murine bone loss model of a critically-sized cranial defect. Using this CF defect model in vivo, we delivered JAG1 with pediatric human bone-derived osteoblast-like (HBO) cells to demonstrate the osteo-inductive properties of JAG1 in human cells and in vitro we utilized the HBO cells to identify the downstream non-canonical JAG1 signaling intermediates as effective bone regenerative treatments. In vitro, we identified an important mechanism by which JAG1 induces pediatric osteoblast commitment and bone formation involving the phosphorylation of p70 S6K. This discovery enables potential new treatment avenues involving the delivery of tethered JAG1 and the downstream activators of p70 S6K as powerful bone regenerative therapies in pediatric CF bone loss.

developmental biology↗

bioRxiv2020

JAGGED1 Stimulates Cranial Neural Crest Cell Osteoblast Commitment Pathways and Bone Regeneration Independent of Canonical NOTCH Signaling

Craniofacial bone loss is a complex clinical problem with limited regenerative solutions. Currently, BMP2 is used as a bone-regenerative therapy in adults, but in pediatric cases of bone loss, it is not FDA-approved due to concerns of life-threatening inflammation and cancer. Development of a bone-regenerative therapy for children will transform our ability to reduce the morbidity associated with current autologous bone grafting techniques. We discovered that JAGGED1 (JAG1) induces cranial neural crest (CNC) cell osteoblast commitment during craniofacial intramembranous ossification, suggesting that exogenous JAG1 delivery is a potential craniofacial bone-regenerative approach. In this study, we found that JAG1 delivery using synthetic hydrogels containing O9-1 cells, a CNC cell line, into critical-sized calvarial defects in C57BL/6 mice provided robust bone-regeneration. Since JAG1 signals through canonical (Hes1/Hey1) and non-canonical (JAK2) NOTCH pathways in CNC cells, we used RNAseq to analyze transcriptional pathways activated in CNC cells treated with JAG1{+/-}DAPT, a NOTCH-canonical pathway inhibitor. JAG1 upregulated expression of multiple NOTCH canonical pathway genes (Hes1), which were downregulated in the presence of DAPT. JAG1 also induced bone chemokines (Cxcl1), regulators of cytoskeletal organization and cell migration (Rhou), signaling targets (STAT5), promoters of early osteoblast cell proliferation (Prl2c2, Smurf1 and Esrra), and, inhibitors of osteoclasts (Id1). In the presence of DAPT, expression levels of Hes1 and Cxcl1 were decreased, whereas, Prl2c2, Smurf1, Esrra, Rhou and Id1 remain elevated, suggesting that JAG1 induces osteoblast proliferation through these non-canonical genes. Pathway analysis of JAG1+DAPT-treated CNC cells revealed significant upregulation of multiple non-canonical pathways, including the cell cycle, tubulin pathway, regulators of Runx2 initiation and phosphorylation of STAT5 pathway. In total, our data show that JAG1 upregulates multiple pathways involved in osteogenesis, independent of the NOTCH canonical pathway. Moreover, our findings suggest that JAG1 delivery using a synthetic hydrogel, is a bone-regenerative approach with powerful translational potential.

genomics↗

bioRxiv2018

A non-canonical JAGGED1 signal to JAK2 mediates osteoblast commitment in cranial neural crest cells

During craniofacial development, cranial neural crest (CNC) cells migrate into the developing face and form bone through intramembranous ossification. Loss of JAGGED1 (JAG1) signaling in the CNC cells is associated with maxillary hypoplasia or maxillary bone deficiency (MBD) in mice and recapitulates the MBD seen in humans with Alagille syndrome. JAGGED1, a membrane-bound NOTCH ligand, is required for normal craniofacial development, and Jagged1 mutations in humans are known to cause Alagille Syndrome, which is associated with cardiac, biliary, and bone phenotypes and these children experience increased bony fractures. Previously, we demonstrated deficient maxillary osteogenesis in Wnt1-cre;Jagged1f/f (Jag1CKO) mice by conditional deletion of Jagged1 in maxillary CNC cells. In this study, we investigated the JAG1 signaling pathways in a CNC cell line. Treatment with JAG1 induced osteoblast differentiation and maturation markers, Runx2 and Ocn, respectively, Alkaline Phosphatase (ALP) production, as well as classic NOTCH1 targets, Hes1 and Hey1. While JAG1-induced Hes1 and Hey1 expression levels were predictably decreased after DAPT (NOTCH inhibitor) treatment, JAG1-induced Runx2 and Ocn levels were surprisingly constant in the presence of DAPT, indicating that JAG1 effects in the CNC cells are independent of the canonical NOTCH pathway. JAG1 treatment of CNC cells increased Janus Kinase 2 (JAK2) phosphorylation, which was refractory to DAPT treatment, highlighting the importance of the non-canonical NOTCH pathway during CNC cells osteoblast commitment. Pharmacologic inhibition of JAK2 phosphorylation, with and without DAPT treatment, upon JAG1 induction reduced ALP production and, Runx2 and Ocn gene expression. Collectively, these data suggest that JAK2 is an essential component downstream of a non-canonical JAG1-NOTCH1 pathway through which JAG1 stimulates expression of osteoblast-specific gene targets in CNC cells that contribute to osteoblast differentiation and bone mineralization.

molecular biology↗