FITC-Dextran is a fluorescent probe for fluorescein isothiocyanate (FITC) dextran (Ex=495 nm; Em=525 nm). In cell permeability studies, FITC-Dextran can assess BBB permeability and BBB disruption [1,2].
When analyse the lysosomal pH in cultured cells using the fluorescent probe fluorescein isothiocyanate (FITC)-dextran together with a dual-emission ratiometric technique suitable for flow cytometry. Fluorescence-labeled dextran is endocytosed and accumulated in the lysosomal compartment. FITC shows a pH-dependent variation in fluorescence when analyzed at maximum emission wavelength and no variation when analyzing at the isosbestic point, thereby the ratio can be used to determine the lysosomal pH[2].Fitc-glucan increased intestinal epithelial paracellular permeability after 21 days of incubation[5]. When examined their expression and FITC-Dextran uptake by various human DC preparations. In contrast to immature Mo-DC, the FITC-dextran uptake by LC was not inhibited effectively by mannose, an inhibitor for MMR-mediated FITC-dextran uptake[7].
After 6 h of fasting in our C3H/HeOu mice, plasma concentrations of 4-kDa FITC-Dextran peaked at 45 min after oral administration[3]. The fluorescence of small vessels and neovascular tufts could be observed clearly following RO injection of 0.05 ml of 25 mg/ml or 50 mg/ml FITC-dextran. No visible damage to tissues adjacent to the injection site was discovered. Vitreous blood flow was gradually reduced from P0 to P5 and eventually disappeared in P17 OIR mice, as demonstrated by FITC-dextran perfusion. The retinal NV areas assessed by isolectin B4 were larger than those assessed by FITC-dextran, but the retinal avascular areas were smaller[4]. When measured fluorescence recovery after photobleaching (FRAP) of fluorescein isothiocyanate (FITC)-labelled 10 and 250 kDa dextran (FITC-Dextran) in isolated rat descending colonic crypts.FRAP of either 10 or 250 kDa FITC-Dextran in crypt lumens was almost complete within 2-3 min. In the presence of amiloride (0.1 mM), or in the absence of Na+, the rate of FITC-Dextran uptake into the crypt lumens was reduced by 70-80 %[6].
References:
[1]: Natarajan R, Northrop N, et,al. Fluorescein Isothiocyanate (FITC)-Dextran Extravasation as a Measure of Blood-Brain Barrier Permeability. Curr Protoc Neurosci. 2017 Apr 10;79:9.58.1-9.58.15. doi: 10.1002/cpns.25. PMID: 28398646; PMCID: PMC5470084.
[2]: Eriksson I, ?llinger K, et,al.Analysis of Lysosomal pH by Flow Cytometry Using FITC-Dextran Loaded Cells. Methods Mol Biol. 2017;1594:179-189. doi: 10.1007/978-1-4939-6934-0_11. PMID: 28456983.
[3]: Woting A, Blaut M. Small Intestinal Permeability and Gut-Transit Time Determined with Low and High Molecular Weight Fluorescein Isothiocyanate-Dextrans in C3H Mice. Nutrients. 2018 May 28;10(6):685. doi: 10.3390/nu10060685. PMID: 29843428; PMCID: PMC6024777.
[4]: Li J, Wu Y, et,al. Retro-orbital injection of FITC-dextran combined with isolectin B4 in assessing the retinal neovascularization defect. BMC Ophthalmol. 2021 May 11;21(1):208. doi: 10.1186/s12886-021-01969-5. PMID: 33975571; PMCID: PMC8112026.
[5]: Sun X, Yang Q, et,al.AMPK improves gut epithelial differentiation and barrier function via regulating Cdx2 expression. Cell Death Differ. 2017 May;24(5):819-831. doi: 10.1038/cdd.2017.14. Epub 2017 Feb 24. PMID: 28234358; PMCID: PMC5423107.
[6]: Thiagarajah JR, Pedley KC, et,al. Evidence of amiloride-sensitive fluid absorption in rat descending colonic crypts from fluorescence recovery of FITC-labelled dextran after photobleaching. J Physiol. 2001 Oct 15;536(Pt 2):541-53. doi: 10.1111/j.1469-7793.2001.0541c.xd. PMID: 11600688; PMCID: PMC2278881.
[7]: Kato M, Neil TK,et,al. Expression of multilectin receptors and comparative FITC-dextran uptake by human dendritic cells. Int Immunol. 2000 Nov;12(11):1511-9. doi: 10.1093/intimm/12.11.1511. PMID: 11058570.
FITC-Dextran 是异硫氰酸荧光素 (FITC) 葡聚糖（Ex=495 nm；Em=525 nm）的荧光探针。在细胞通透性研究中,FITC-Dextran 可以评估 BBB 通透性和 BBB 破坏[1,2]。
当使用荧光探针异硫氰酸荧光素 (FITC)-葡聚糖和适用于流式细胞术的双发射比率技术分析培养细胞中的溶酶体 pH 值时。荧光标记的葡聚糖被内吞并积聚在溶酶体隔室中。 FITC 在最大发射波长分析时显示荧光的 pH 依赖性变化,而在等吸光点分析时没有变化,因此该比率可用于确定溶酶体 pH[2]。Fitc-葡聚糖培养 21 天后肠上皮细胞旁通透性增加[5]。当检查它们的表达和 FITC-葡聚糖被各种人类 DC 制剂摄取时。与未成熟的 Mo-DC 相比,LC 对 FITC-葡聚糖的摄取没有受到甘露糖的有效抑制,甘露糖是 MMR 介导的 FITC-葡聚糖摄取的抑制剂[7]。
在我们的 C3H/HeOu 小鼠禁食 6 小时后,4-kDa FITC-葡聚糖的血浆浓度在口服给药后 45 分钟达到峰值[3]。 RO注射0.05 ml 25 mg/ml或50 mg/ml FITC-葡聚糖后,可以清楚地观察到小血管和新生血管簇的荧光。没有发现注射部位附近组织的可见损伤。玻璃体血流从 P0 到 P5 逐渐减少,最终在 P17 OIR 小鼠中消失,如 FITC-葡聚糖灌注所证明的。异凝集素 B4 评估的视网膜 NV 区域大于 FITC-葡聚糖评估的视网膜 NV 区域,但视网膜无血管区域较小 [4]。当在离体大鼠降结肠隐窝中测量异硫氰酸荧光素 (FITC) 标记的 10 和 250 kDa 葡聚糖 (FITC-葡聚糖) 光漂白 (FRAP) 后的荧光恢复时。隐窝腔中 10 或 250 kDa FITC-葡聚糖的 FRAP 几乎完成2-3 分钟内在存在阿米洛利 (0.1 mM) 或不存在 Na+ 的情况下,FITC-葡聚糖摄取到隐窝腔内的速率降低了 70-80%[6]。