Evaluation of cationic polyamidoamine dendrimers’ dermal toxicity in the rat skin model

Abstract

Polyamidoamine (PAMAM) dendrimers are multi-branched, three-dimensional polymers with unique architecture, which makes these molecules attractive for medical and pharmaceutical applications. Using PAMAM as drug carriers for topical delivery might be beneficial as they only produce a transient effect without skin irritation. To evaluate the dermal toxicity of cationic PAMAM dendrimers generation 2 and generation 3, skin irritation studies were performed in vivo in the rat skin model. After 10 days topical application of various concentrations of PAMAM-NH2 (0.3 mg/mL, 3 mg/mL, 6 mg/mL, 30 mg/mL, 300 mg/mL), skin irritation was evaluated by visual, histopathological, and immunohistochemical examination. Microscopic assessment after hematoxylin-eosin staining revealed significant morphological changes of epidermal cells after application of PAMAM-NH2 at a concentration of ≥6 mg/mL. Morphological alterations of epidermal cells included cytoplasmic vacuolization of keratinocytes in the basal and spinous layers. Cytomorphological changes in keratinocytes, overall picture of the epidermis, and histopathological changes in the dermis were dose dependent. Detected alterations concerned hyperplasia of connective tissue fibers and leukocyte infiltration. Visible granulocyte infiltration in the upper dermis and sockets formed by necrotic, cornified cells in the hyperplastic foci of epithelium were also noted. Immunohistochemical analyses revealed that increased nuclear immunoreactivity to PCNA correlated with the concentration of PAMAM-NH2, but no significant differences in the cell proliferation activity in skin treated with PAMAM-NH2 generation 2 or generation 3 were observed. Significantly higher expression of PCNA extended throughout the skin layers might suggest abnormal cell proliferation, which, as a consequence, might even lead to neoplastic changes.

<p>Effect of 2nd and 3rd generation PAMAM dendrimers on proliferation, differentiation, and pro-inflammatory cytokines in human keratinocytes and fibroblasts</p>

“…Some preparations cause a disruptor in the metabolism of keratinocytes and their abnormal keratosis, consisting of the separation of individual cells in the spinous layer, with formation of horn seeds and the formation of so-called round cells44 that we also observed in our study. This may confirm the results of Winnicka’s research, in which she observed that the morphological changes of epidermal cells of rats treated with PAMAM dendrimers included cytoplasmic vacuolization of keratinocytes in the basal and spinous layers 17…”

Immunoreactivity changes of human serum albumin and alpha-1-microglobulin induced by their interaction with dendrimers

“…It can be divided in 2 main directions, the first being where dendrimers are used to improve the action of antibodies [36,37] or multivalent antibody-antigen interactions [40,41], to present new kinds of adjuvants [42][43][44], to improve visualization of proteins [45,46], to construct dendrimerconjugated peptide vaccines [47,48] and dendrimer-antibody complex systems for siRNA or drug delivery [49][50][51]. In second direction, immunoreactivity of proteins as well as the interaction of dendrimers with antibodies are examined as a side effect of possible application of dendrimers [52][53][54][55][56]. In particular, Wangler et al [53] showed that in antibody-dendrimer conjugates, the number, but not the size of the dendrimers, determines the immunoreactivity of these complexes.…”

The Influence of Chitosan Cross-linking on the Properties of Alginate Microparticles with Metformin Hydrochloride—In Vitro and In Vivo Evaluation

“…Tissue sections were passed through series of alcohol for dehydration (70%, 90% and 100%) and examined using a light microscope Olympus BX41 (Olympus Corporation, Tokyo, Japan) at 200× magnifications interfaced with an image analysis system. The images were captured using a DP12 camera (Olympus Corporation, Tokyo, Japan) [ 54 , 55 ].…”