Formulation of a Novel Polymeric Hydrogel Membrane for Periodontal Tissue Regeneration Using Tricalcium Phosphate-Alginate Reinforcement.

BACKGROUND: The primary goal of periodontal therapy is to facilitate the regeneration of tissues damaged by periodontal disease. In recent years, there has been a growing utilization of guided tissue regeneration (GTR) membranes with bioabsorbable properties as these membranes are increasingly employed to guide the growth of gingival tissue away from the root surface. Both resorbable and non-resorbable membranes currently employed act as physical barriers, preventing the ingrowth of connective and epithelial tissues into the defect and thereby facilitating periodontal tissue regeneration. OBJECTIVE: This study aimed to develop a polymeric hydrogel membrane reinforced with tricalcium phosphate (TCP)-alginate and assess its potential for periodontal regeneration. MATERIALS AND METHODS: TCP nanoparticles were incorporated into the alginate mixture to form TCP alginate. Subsequently, the mixture was cross-linked with calcium chloride to produce a TCP-alginate polymeric hydrogel membrane. The membrane underwent hemocompatibility analysis, and also scanning electron microscopy and Fourier-transform infrared (FTIR) spectroscopy analyses were done. RESULTS: The SEM analysis revealed granulations and a bonded thread-like structure in the membrane, indicative of favorable conditions for cell attachment necessary for periodontal regeneration. FTIR analysis showed characteristic peaks in the spectrum, including those attributed to phosphate ion (PO4-3) at 1000.85 cm-1 and 600 cm-1, indicating the presence of ß-TCP phases. Hemocompatibility assessment demonstrated a hemolysis rate of less than 5% for the TCP-alginate membrane, which is found to be within the limits. CONCLUSION: The developed TCP-reinforced alginate membrane exhibited hemocompatibility and safety, suggesting its suitability for utilization in periodontal therapy as an effective regenerative material.

Generation of pancreatic hormone-expressing islet-like cell aggregates from murine adipose tissue-derived stem cells.

The success of cell replacement therapy for diabetes depends on the availability and generation of an adequate number of islets, preferably from an autologous origin. Stem cells are now being probed for the generation of physiologically competent, insulin-producing cells. In this investigation, we explored the potential of adipose tissue-derived stem cells (ASCs) to differentiate into pancreatic hormone-expressing islet-like cell aggregates (ICAs). We initiated ASC culture from epididymal fat pads of Swiss albino mice to obtain mesenchymal cells, murine epididymal (mE)-ASCs. Subsequent single-cell cloning resulted in a homogeneous cell population with a CD29(+)CD44(+)Sca-1(+) surface antigen expression profile. We formulated a 10-day differentiation protocol to generate insulin-expressing ICAs from mE-ASCs by progressively changing the differentiation cocktail on day 1, day 3, and day 5. Our stage-specific approach successfully differentiated mesodermic mE-ASCs into definitive endoderm (cells expressing Sox17, Foxa2, GATA-4, and cytokeratin [CK]-19), then into pancreatic endoderm (cells expressing pancreatic and duodenal homeobox [PDX]-1, Ngn3, NeuroD, Pax4, and glucose transporter 2), and finally into cells expressing pancreatic hormones (insulin, glucagon, somatostatin). Fluorescence-activated cell sorting analysis showed that day 5 ICAs contained 64.84% +/- 7.03% PDX-1(+) cells, and in day 10 mature ICAs, 48.17% +/- 3% of cells expressed C-peptide. Day 10 ICAs released C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Electron microscopy of day 10 ICAs revealed the presence of numerous secretory granules within the cell cytoplasm. Calcium alginate-encapsulated day 10 ICAs (1,000-1,200), when transplanted i.p. into streptozotocin-induced diabetic mice, restored normoglycemia within 2 weeks. The data presented here demonstrate the feasibility of using ASCs as a source of autologous stem cells to differentiate into the pancreatic lineage.

A DNA nanomachine that maps spatial and temporal pH changes inside living cells.

DNA nanomachines are synthetic assemblies that switch between defined molecular conformations upon stimulation by external triggers. Previously, the performance of DNA devices has been limited to in vitro applications. Here we report the construction of a DNA nanomachine called the I-switch, which is triggered by protons and functions as a pH sensor based on fluorescence resonance energy transfer (FRET) inside living cells. It is an efficient reporter of pH from pH 5.5 to 6.8, with a high dynamic range between pH 5.8 and 7. To demonstrate its ability to function inside living cells we use the I-switch to map spatial and temporal pH changes associated with endosome maturation. The performance of our DNA nanodevices inside living systems illustrates the potential of DNA scaffolds responsive to more complex triggers in sensing, diagnostics and targeted therapies in living systems.