Studies on small (<350 ?m) alginate-poly-L-lysine microcapsules. III. Biocompatibility of smaller versus standard microcapsules

Abstract

Microencapsulation of islets of Langerhans has been proposed as a means of preventing their immune destruction following transplantation. Microcapsules of diameters <350 microm made with an electrostatic pulse system present many advantages relative to standard microcapsules (700-1500 microm), including smaller total implant volume, better insulin kinetics, better cell oxygenation, and accessibility to new implantation sites. To evaluate their biocompatibility, 200, 1000, 1120, 1340, or 3000 of these smaller microcapsules (<350 microm) or 20 standard microcapsules (1247+/-120 microm) were implanted into rat epididymal fat pads, retrieved after 2 weeks, and evaluated histologically. The average pericapsular reaction increased with the number of small microcapsules implanted (p<0.05; 3000 vs. 200, 3000 vs. 1000, and 1000 vs. 200 microcapsules). At equal volume and alginate content, standard microcapsules caused a more intense fibrosis reaction than smaller microcapsules (p<0.05). In addition, 20 standard microcapsules elicited a stronger pericapsular reaction than 200 and 1000 smaller microcapsules (p<0.05) although the latter represented a 3.4-fold larger total implant surface exposed. We conclude that microcapsules of diameters <350 microm made with an electrostatic pulse system are more biocompatible than standard microcapsules.

Measurement of particle diameter of Lactobacillus acidophilus microcapsule by spray drying and analysis on its microstructure

“…Therefore, there should be an optimal particle diameter not only to have a good protection on L. acidophilus and achieve maximal shelf stability, but also have a fine distribution of microcapsule in the products. According to the report of Robitaille et al (1999) that the standard smaller microcapsule was designated as\350 lm and according to the size of L. acidophilus (0.6-0.9 lm 9 1.5 lm), the size of L. acidophilus microcapsule should be between 1.5 lm and 350 lm.…”

Characterisation of the Poly-(Vinylpyrrolidone)-Poly-(Vinylacetate-Co-Crotonic Acid) (PVP:PVAc-CA) Interpolymer Complex Matrix Microparticles Encapsulating a Bifidobacterium lactis Bb12 Probiotic Strain

“…Small microparticles are preferred as they ensure even distribution of the encapsulated probiotic strain that will be active in the final products [38]. The standard size of the microcapsules should be \350 lm [27]. Microcapsules should be of small diameter (\100 lm) for higher stability and minimal undesirable organoleptic qualities when incorporated into foods [24].…”

CHO immobilization in alginate/poly-l-lysine microcapsules: an understanding of potential and limitations

“…Size of microcapsules is a critical parameter for the encapsulation of micro-organisms and animal cells, since large microcapsules (>1mm) will suffer from diffusion limitations resulting in reduced cell growth and necrosis within the core (Glacken et al 1983;Robitaille et al 1999). Nevertheless, decreasing the microcapsule size from 800 to 500 lm did not improve colonization by cells (Table 1, Fig.…”

“…Residual core alginate could interact with cations present in the culture medium and, depending on whether the cations are mono-or di-valent, decrease or increase the viscosity. Thus, since the alginate itself has been shown to be non-cytotoxic (Robitaille et al 1999), this suggests that it is the molecular volume of the hydrated alginate which is responsible for limiting the space available for cell colonization. …”