Biodegradation of Chitosan-Tripolyphosphate Beads: In Vitro and In Vivo Studies

Figures & data

Table 1 The water uptake and size distribution of chitosan beads

Bead type	Loading^[1]	Size distribution (µm)^[2]	Water uptake (w/w)^[3]
Chitosan-TPP (C)	Empty	1200–1500	7,1
	BSA-loaded	1400–1800	8,2
Alginate coated chitosan-TPP (CA)	Empty	1100–1450	7,0
	BSA-loaded	1250–1600	7,4
Crosslinked-chitosan-TPP (CGA)	Empty	900–1200	3,7
	BSA-loaded	1000–1400	3,9

^[1]Empty: standard chitosan-TPP beads; BSA-loaded: beads loaded with bovine serum albumin at a concentration of 5.0 mg/ml gel solution.

^[2]Diameter range of 60 beads from 3 different batches, for each experimental group.

^[3]Mean water uptake value of 1.000 g swollen beads from 3 different batches, for each experimental group.

Figure 1 Scanning electron micrographs demonstrating the surface morphology of (A) empty and (B) BSA-loaded chitosan-TPP beads. C and D are the surface details of B.

Figure 2 In vitro degradation of chitosan beads in dissolution solutions of PBS at (A) pH 7.4 and (B) pH 6.5 (37°C; static conditions, weekly fresh medium changes). C: chitosan-TPP; CA: alginate-coated chitosan-TPP; CGA: glutaraldehyde-crosslinked chitosan-TPP. All values presented are given as mean ± SD.

Figure 3 Histological appearance of chitosan beads retrieved at 2 months post-implantation from the epigastric groin fascia of Wistar rats (H&E staining). A and B: chitosan-TPP (C) beads; C and D: alginate-coated chitosan-TPP (CA) beads; E and F: glutaraldehyde-crosslinked chitosan-TPP (CGA) beads. F is the detail of E. FP: fat pad; arrows: capillaries. Scale bars: 200 µm.

Figure 4 Histological appearance of chitosan beads retrieved at 6 months post-implantation from the epigastric groin fascia of Wistar rats (H&E staining). A and B: chitosan-TPP (C) beads; C and D: alginate-coated chitosan-TPP (CA) beads; E and F: glutaraldehyde-crosslinked chitosan-TPP (CGA) beads. F is the detail of E. FP: fat pad; arrows: capillaries. Scale bars: 200 µm.

Table 2 Histomorphometric analysis on the in vivo biodegradation of chitosan beads^[1]

Bead type^[2]	2 months (%)^[3]	6 months (%)^[3]
Chitosan-TPP (C)	7.7 ± 3.4 (*)	85.4 ± 4.7 (*, ‡)
Alginate coated chitosan-TPP (CA)	4.9 ± 2.3 (**)	50.2 ± 4.3 (**, ∥)
Crosslinked-chitosan-TPP (CGA)	2.7 ± 1.2 (***)	24.8 ± 2.6 (***, ‡, ∥)

^[1]Performed on histology sections to determine the level of in vivo biodegradation of C, CA and CGA beads, at 2 and 6 months after implantation.

^[2]Twelve counts from 6 different histology sections were performed for each experimental group.

^[3]Data were expressed as the mean ± SD. Statistical analysis was carried out using the unpaired Student's t test for the histomorphometric data. A value of P < 0.05 was considered to be statistically significant [(*,*); (**,**); (***,***);(‡,‡); (∥, ∥)].