Expression of pro-angiogenic/pro-islet cytokines in subcutaneous implants in diabetic mice.

<p>The expression of GM-CSF (<b>A</b>), SCF (<b>B</b>), SDF-1α (<b>C</b>), VCAM-1 (<b>D</b>) and VEGF (<b>E</b>) protein in hydrogels explanted at 1 (black bars), 2 (grey bars) and 6 weeks (white bars) was normalized to the levels in the collagen hydrogel at their respective time point (<i>n</i>=3 each). <i>P</i>-values in (A): *<i>p</i>=0.007 and <i>p</i>=0.04 vs. 1 week collagen-chitosan and collagen-chitosan+CAC implants, respectively; ^<b>†</b><i>p</i>=0.02; ^{<b>††</b>}<i>p</i>=0.005; and ^{<b>†††</b>}<i>p</i><0.05). In (B): *<i>p</i>≤0.004 vs. collagen+CAC and collagen-chitosan+CAC implants at 1 week; ^<b>†</b><i>p</i>=0.002; and ^{<b>††</b>}<i>p</i>=0.01. In (C): *<i>p</i>=0.01 vs. collagen+CAC at 1 week. In (D): *<i>p</i>=0.01 vs. collagen at 2 weeks; **<i>p</i>=0.004 vs. collagen+CAC at 6 weeks; ***<i>p</i>=0.0002 vs. collagen+CAC at 6 weeks. In (E): *<i>p</i>≤0.007 vs. collagen+CAC and collagen-chitosan+CAC at 1 week; and ^<b>†</b><i>p</i>=0.03.</p

Expression of pro-angiogenic/anti-islet cytokines in subcutaneous implants in diabetic mice.

<p>The expression of IL-1β (<b>A</b>), lymphotactin (<b>B</b>), MCP-1 (<b>C</b>), MCP-5 (<b>D</b>), M-CSF (<b>E</b>), RANTES (<b>F</b>), TARC (<b>G</b>) and TNF-α (<b>H</b>) protein in hydrogels explanted at 1 (black bars), 2 (grey bars) and 6 weeks (white bars) was normalized to the levels in the collagen hydrogel at their respective time point (<i>n</i>=3 each). <i>P</i>-values in (A): *<i>p</i>=0.05 vs. collagen-chitosan+CAC at 1 week; and ^<b>†</b><i>p</i>≤0.003. In (B): *<i>p</i>=0.03 vs. collagen+CAC at 1 week; **<i>p</i>=0.04 vs. collagen at 2 weeks; and ^<b>†</b><i>p</i>≤0.02. In (C): *<i>p</i>=0.04 vs. collagen at 1 week; **<i>p</i>=0.003 vs. collagen at 1 week; ***<i>p</i>≤0.01 vs. collagen and collagen+CAC hydrogels at 2 weeks; ****<i>p</i>=0.01 vs. collagen and collagen+CAC at 6 weeks; and ^<b>†</b><i>p</i>≤0.006 vs. collagen+CAC at 2 and 6 weeks. In (D): ^<b>†</b><i>p</i>=0.04. In (E): *<i>p</i>≤0.04 vs. all other hydrogels at 1 week; **<i>p</i>≤0.003 vs. all other hydrogels at 2 weeks; ***<i>p</i>=0.02 vs. collagen at 6 weeks; and ^<b>†</b><i>p</i>≤0.02. In (F): *<i>p</i>=0.009 vs. collagen+CAC at 1 week; **<i>p</i>≤0.01 vs. collagen and collagen+CAC at 2 weeks; ^<b>†</b><i>p</i>=0.04; and ^{<b>††</b>}<i>p</i>≤0.02. In (G): *<i>p</i>≤0.02 vs. all other implants at 1 week; ^<b>†</b><i>p</i>≤0.007; ^{<b>††</b>}<i>p</i>=0.03; and ^{<b>†††</b>}<i>p</i>≤0.008.</p

Expression of anti-angiogenic/anti-islet cytokines in subcutaneous implants in diabetic mice.

<p>The expression of BLC (<b>A</b>), IFN-λ (<b>B</b>), IL12p70 (<b>C</b>), MIG (<b>D</b>), and PF-4 (<b>E</b>) protein in hydrogels explanted at 1 (black bars), 2 (grey bars) and 6 weeks (white bars) was normalized to the levels in the collagen hydrogel at their respective time point (<i>n</i>=3 each). <i>P</i>-values in (A): ^<b>†</b><i>p</i>=0.02. In (B): *<i>p</i>=0.02 vs. collagen at 6 weeks; ^<b>†</b><i>p</i>=0.01; and ^{<b>††</b>}<i>p</i>=0.04. In (C): *<i>p</i>≤0.02 vs. collagen and collagen+CAC implants at 1 week; ^<b>†</b><i>p</i>=0.02; and ^{<b>††</b>}<i>p</i>=0.02). In (D): *<i>p</i>=0.02 vs. collagen-chitosan at 1 week; **<i>p</i>≤0.02 vs. collagen and collagen-chitosan at 1 week; ***<i>p</i>≤0.01 vs. all other implants at 2 weeks; ****<i>p</i>≤0.001 vs. all other implants at 6 weeks; *****<i>p</i>=0.03 vs. collagen+CAC at 6 weeks; ^<b>†</b><i>p</i>=0.02; ^{<b>††</b>}<i>p</i><0.0001; and ^{<b>†††</b>}<i>p</i>=0.009. In (E): *<i>p</i>≤0.03 vs. collagen-chitosan+CAC and collagen+CAC implants at 1 week; **<i>p</i>≤0.006 vs. all other implants at 2 weeks; ***<i>p</i>≤0.01 vs. collagen-chitosan and collagen-chitosan+CAC at 6 weeks; ****<i>p</i>=0.007 vs. collagen-chitosan+CAC at 6 weeks; ^<b>†</b><i>p</i><0.0001; and ^{<b>††</b>}<i>p</i><0.0001.</p

Evaluation of a Collagen-Chitosan Hydrogel for Potential Use as a Pro-Angiogenic Site for Islet Transplantation

<div><p>Islet transplantation to treat type 1 diabetes (T1D) has shown varied long-term success, due in part to insufficient blood supply to maintain the islets. In the current study, collagen and collagen:chitosan (10:1) hydrogels, +/- circulating angiogenic cells (CACs), were compared for their ability to produce a pro-angiogenic environment in a streptozotocin-induced mouse model of T1D. Initial characterization showed that collagen-chitosan gels were mechanically stronger than the collagen gels (0.7kPa vs. 0.4kPa elastic modulus, respectively), had more cross-links (9.2 vs. 7.4/µm²), and were degraded more slowly by collagenase. After gelation with CACs, live/dead staining showed greater CAC viability in the collagen-chitosan gels after 18h compared to collagen (79% vs. 69%). <i>In vivo</i>, collagen-chitosan gels, subcutaneously implanted for up to 6 weeks in a T1D mouse, showed increased levels of pro-angiogenic cytokines over time. By 6 weeks, anti-islet cytokine levels were decreased in all matrix formulations ± CACs. The 6-week implants demonstrated increased expression of VCAM-1 in collagen-chitosan implants. Despite this, infiltrating vWF⁺ and CXCR4⁺ angiogenic cell numbers were not different between the implant types, which may be due to a delayed and reduced cytokine response in a T1D versus non-diabetic setting. The mechanical, degradation and cytokine data all suggest that the collagen-chitosan gel may be a suitable candidate for use as a pro-angiogenic ectopic islet transplant site. </p> </div

Characterization of hydrogel fiber cross-linking.

<p>Representative SEM images of collagen (<b>A</b>) or collagen (coll)-chitosan (<b>B</b>) hydrogels. Total cross-links per image (<b>C</b>) as well as distance (µm) between cross-links (<b>D</b>) were quantified (*<i>p</i>=0.046; **<i>p</i>=0.03; <i>n</i>=4 each). </p

Degradation and elastic modulus of hydrogels.

<p>(<b>A</b>) Collagen (black bars) and collagen-chitosan (gray bars) hydrogels were incubated in 100U collagenase and the residual mass was determined over time (*<i>p</i>≤0.03 vs. collagen at the same time-point; **<i>p</i><0.0001 vs. collagen at 2 hours; ***<i>p</i><0.0001 vs. collagen-chitosan at 3h; <i>n</i>=4 each). (<b>B</b>) Stress/strain curve for collagen and collagen-chitosan hydrogels. (<b>C</b>) The elastic modulus for the collagen and collagen-chitosan hydrogel samples (*<i>p</i><0.0001; <i>n</i>=8).</p

Representative images of HPS-stained collagen and collagen-chitosan hydrogels (±CACs) explanted at 2 and 6 weeks.

<p>Representative images of HPS-stained collagen and collagen-chitosan hydrogels (±CACs) explanted at 2 and 6 weeks.</p

Additional file 3 of The dynamic changes and sex differences of 147 immune-related proteins during acute COVID-19 in 580 individuals

Additional file 3: Protein correlation heatmaps

Additional file 1 of The dynamic changes and sex differences of 147 immune-related proteins during acute COVID-19 in 580 individuals

Additional file 1: List of immunity-related proteins measured

Additional file 5 of The dynamic changes and sex differences of 147 immune-related proteins during acute COVID-19 in 580 individuals

Additional file 5: Inferred protein levels over time