Quality control of the biopolymer and cytotoxicity testing
The biopolymer used in this investigation expressed a whole set of quality control measures as it is produced under GMP conditions. The biopolymer was highly biocompatible, as demonstrated in vitro and in vivo. For each lot a whole set of quality controls was routinely performed, such as cytotoxicity testing in three different batches of the biopolymer using three different cell lines of diverse origin. No cytotoxic effect was observed for three different batches of the biopolymer using the three different cell lines (Fig. 1).
In vitro release of PTH from human encapsulated parathyroid tissue
The median intact PTH release per microcapsule was calculated over two hour period of incubation in serum-free medium using parathyroid tissue obtained from three different patients. At day one PTH release was below 500 pg/mL for all tissues with a constant increase in the following days (Fig. 2).
Microencapsulated human parathyroid tissue showed an excellent viability over 7/8 days in culture (Fig. 3). buy generic viagra on online pharmacy shop
Figure 1. Cytotoxicity testing was performed for three biopolymer solutions (a-c) using three different cell lines (L-929, VERO, and NHDF). The metabolic activity of the cell lines is expressed as percentage on negative controls. The positive control (pos. control) is represented by RPMI 1640 culture medium containing 50 ng/mL CuSO4.
Figure 2 – PTH release from encapsulated human parathyroid tissue fragments obtained from three different donors. Intact PTH release over 2 hours of incubation in serum-free medium was evaluated for a period up to 8 days. The mean intact PTH release was elaborated from the release from 10 microcapsules and expressed as pg/2hr/capsule.
Figure 3 – Histological sections of encapsulated human parathyroid fragments. H&E staining showed a conserved morphology after 7 days in culture with serum-free culture medium.