<p>We successfully transfected a well-established lung epithelial cell line CFBE41o- with our chitosan-RNA complexes using our synthesized pcDNA 3.1 eYFP mRNA, which were subsequently incubated with SORT LNPs for packaging. The goal was to encapsulate the chitosan-RNA complexes within the LNPs to enhance mRNA delivery to cells. After formulation, the LNP Chitosan-RNA complexes were transfected into CFBE41o- cells, to assess the efficiency of mRNA delivery and expression.</p>
<p>We tested two different chitosan and mRNA concentrations (always used both in the same concentrations), 50 ng/µl and 500 ng/µl, in combination with our LNP to assess their impact on transfection efficiency. Interestingly, both concentrations resulted in similarly high levels of transfection, as evidenced by the fluorescence microscopy images, further validation is necessary to confirm these results.</p>
<p>Fluorescence microscopy was performed 24 hours post-transfection to evaluate the expression of the YFP reporter gene encoded by the pcDNA 3.1 eYFP mRNA. This reporter gene serves as an indicator of successful transfection and translation of the mRNA into protein. The results of the fluorescence microscopy were highly positive and aligned with our expectations, indicating efficient delivery, uptake, and expression of the mRNA in the CFBE41o- cells.</p>
<H4text="Flow cytometry"/>
<p>We tested two different chitosan and mRNA concentrations (always used both in the same concentrations), 50 ng/µl and 500 ng/µl, in combination with our LNP to assess their impact on transfection efficiency. Interestingly, both concentrations resulted in similarly high levels of transfection, as evidenced by the fluorescence microscopy images, further validation is necessary to confirm these results.</p>
Overlay of phase contrast and fluorescence microscopic images of with SORT + chitosan 500 transfected CFBE41o- cells at 20x magnification after 48 h post-transfection recorded with Leica DMI6000 B.
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<p>The sample containing 500 ng/µl of chitosan and pcDNA 3.1 eYFP mRNA, encapsulated within SORT LNPs, exhibited fluorescence 24 hours post-transfection (Figure 30). This result indicates that the RNA was successfully delivered into the CFBE41o- cells, where it was transcribed and translated into the YFP protein. The presence of YFP fluorescence confirms not only successful transfection but also robust expression of the reporter gene.</p>
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<p>In the sample containing 50 ng/µl of chitosan and pcDNA 3.1 eYFP mRNA was used, which is tenfold lower than the chitosan and mRNA concentration used in the chitosan500 sample (see above). Despite the lower mRNA concentration, fluorescence was still observed (Figure 31) indicating that the mRNA was efficiently delivered and expressed in the CFBE41o- cells. This result suggests that even at lower mRNA doses, the system can achieve successful transfection and gene expression. We are planning to perform a more detailed comparison of fluorescence intensity between the chitosanRNA500 and chitosanRNA50 samples and even lower concentrations to assess the relationship between mRNA dose and expression level.</p>
Overlay of phase contrast and fluorescence microscopic images of with SORT + chitosan 50 transfected CFBE41o- cells at 20x magnification after 48 h post-transfection recorded with Leica DMI6000 B.
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<p>The samples containing only chitosan (Figure 32) and only SORT LNP (Figure 33) without any mRNA, did not exhibit any detectable fluorescence. This result is consistent with expectations, as chitosan alone and SORT LNP alone are not fluorescent. These samples served as important negative controls to confirm that the chitosan itself and the SORT LNP itself don't interfere with the fluorescence signal.</p>
Overlay of phase contrast and fluorescence microscopic images of with SORT transfected CFBE41o- cells at 20x magnification after 48 h post-transfection recorded with Leica DMI6000 B.
Overlay of phase contrast and fluorescence microscopic images of with chitosan transfected CFBE41o- cells at 20x magnification after 48 h post-transfection recorded with Leica DMI6000 B.
Overlay of phase contrast and fluorescence microscopic images of untransfected CFBE41o- cells at 20x magnification after 48 h post-transfection recorded with Leica DMI6000 B.
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<p>The untreated control, which did not receive any chitosan, RNA, or LNPs, did not show any fluorescence (Figure 34). This negative control confirms that the cells themselves do not express YFP under normal conditions, and that any observed fluorescence in the experimental groups is directly attributable to the transfection and expression of the delivered RNA.</p>
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<p>The results demonstrate that chitosan-RNA complexes, when packaged with SORT LNPs, can efficiently deliver mRNA into CFBE41o- cells and facilitate the expression of a YFP reporter gene. Furthermore, the absence of fluorescence in the control samples validates the specificity of the system, ensuring that the fluorescence signal is solely due to the delivered mRNA and not from other components of the system. Additional testing, such as flow cytometry analysis, is planned to provide a more quantitative assessment of transfection efficiency. This would allow us to accurately determine whether there are subtle differences between the two concentrations that were not detectable by microscopy alone.</p>
