Development of a new decellularization protocol for the whole porcine heart

BACKGROUND

Cardiovascular diseases are the leading cause of death in many countries. Advances in technology have been promoted in this regard, especially in tissue engineering, to meet the need for tissue or organ grafts. In this way, the porcine model has been used due to its morphophysiological similarity between the human species, mainly regarding the cardiovascular system. Tissue engineering is employed using biological scaffolds that are currently derived from porcine. These scaffolds are produced by decellularization, a process to remove cells aiming to maintain only its three-dimensional structure, formed by extracellular matrix (ECM). Its main objective is to produce organs through recellularized scaffolds that could eventually substitute the ones with impaired functions.

AIM

In this way, the present study aimed to establish a new protocol for porcine heart decellularization with potential application on tissue engineering.

METHODS

A porcine heart aorta was cannulated with a silicon tube, and the organ was washed in 0.1% phosphate-buffered saline through a peristaltic pump (Harvard Peristaltic Pump - Harvard Apparatus). After that, deionized water was introduced in the same system. The decellularization procedure was carried out using ionic and non-ionic detergents, namely 4% sodium dodecyl sulfate (SDS) and 1% Triton X-100, respectively. SDS was perfused through myocardial circulation at 400 mL/min for 24 h for 6 days. Subsequently, the heart was infused with Triton X-100 and washed by PBS and water for 24 h. The heart volume was measured before and after the recellularization. After macroscopic evaluation, the heart samples were processed and stained by Hematoxylin and Eosin, Masson's Trichrome, Weigert-Van Gieson, Alcian Blue, and Pricrosirius Red techniques for microscopic analysis. To observe the cell adhesion, the recellularization was provided in this scaffold, which was analyzed under immunofluorescence and scanning electronic microscopy.

RESULTS

The protocol provided cells remotion, with adequate concentration of remaining DNA. ECM components as collagen type I, elastin, and glycosaminoglycans were successfully maintained. The scaffold showed a high cells adherence and proliferation in the recellularization process.

CONCLUSION

According to results, the protocol described in this work preserved the ECM components and the organ architecture, minimizing ECM loss and being possible to state that it is a promising approach to tissue bioengineering.

RELEVANCE FOR PATIENTS

This study provides a protocol for whole porcine heart decellularization, which will ultimately contribute to heart bioengineering and may support further studies on biocompatibility relationship of new cells with recellularized scaffolds.

Comparative study of the effectiveness and residual effect of preoperative antisepsis with 4% chlorhexidine gluconate associated with 70% ethyl alcohol and 0.5% alcoholic chlorhexidine gluconate in dogs

The effectiveness of antisepsis of surgical sites in 20 animals (canine species) was compared and subdivided into two groups, using 4% chlorhexidine gluconate associated with alcohol (group 1) and 0.5% chlorhexidine gluconate (group 2). The samples were collected through skin swab after trichotomy (T1), after definitive antisepsis (T2) and one hour after the use of antiseptic (T3), and then submitted to the count of colony forming units (CFU). In both groups, bacterial growth occurred in T1; in T2, the reduction of CFUs was significant for both groups (G1 and G2); however, if we consider absolute values, we can see in T1 a greater amount of CFUs in G2, and when evaluating the results of T2, we can see values which are very similar between G1 and G2, which may suggest greater efficiency of G2 in initial times after antisepsis. In T3, the reduction of CFUs was more effective for G1, suggesting a greater residual effect when compared to G2. Both antiseptic protocols were effective as they significantly reduced the number of skin bacteria, both in T2 and T3.

The comparative aspects of hystricomorph subplacenta: potential endocrine organ

Background

The placenta of hystricomorph rodents, lagomorphs and some primates includes an unusual structure, termed a subplacenta, which essentially consists of trophoblastic cells located deep to the central implantation site within the area of decidualization. It has been suggested that the subplacenta is functionally important, although considerable controversy remains on the issue. In this context, our objective was to compare the architecture and structure of the subplacentas of different hystricomorph species, to investigate the possibility that it is active in hormone synthesis.

Methods

In total, the placentas of 3 capybaras (Hydrochaeris hydrochaeris), 2 pacas (Agouti paca), 5 agoutis (Dasyprocta leporina), 5 rock cavies (Kerodon rupestris) and 3 guinea pigs (Cavia porcellus) at different stages of pregnancy (early, middle and near term) were used for gross and microscopic examination. This included the preparation of latex injection casts, immunohistochemistry for steroidogenic enzymes, scanning and transmission electron microscopy. Tissue steroid concentrations were also determined.

Results

The gross morphology and microvascular arrangement of the subplacentas were similar among the hystricomorphs studied including ultra-structural verification of cytotrophoblast and syncytiotrophoblast in all species. In guinea pigs, trophoblast cells exhibited characteristics consistent with intense metabolic and secretory activity in general. However, immuno-histochemical evidence also indicated that subplacental trophoblast expressed key steroidogenic enzymes, mainly in the chorionic villus region, consistent with tissue steroid concentrations.

Conclusions

The subplacentas within placentas of hystricomorph rodent species are structurally similar and, in guinea pigs, have potential for steroid hormone secretion from, at least the early stages of pregnancy.

A study on the morphoquantitative and cytological characteristics of the bulbar conjunctiva of the maned wolf (Chrysocyon brachyurus; Illiger, 1815)

The maned wolf, Chrysocyon brachyurus, is a near-threatened carnivore inhabiting the Brazilian Cerrado. Few studies have been conducted on this species, and even fewer have explored its ophthalmological characteristics. Vision is critical to wild canids; thus, this study aimed to provide a morphoquantitative description of the bulbar conjunctiva of the maned wolf using cytological and histological analyses. Ten healthy maned wolves from a conservational centre, including 4 females and 6 males aged 1-12 years (6.5 ± 2.8), were included in the study. The samples for cytological analysis were collected from the inferior conjunctival sac using a cytobrush, and conjunctival tissue was collected for histological analysis from the temporal canthus zone. The cytological samples were stained using the Papanicolaou method, and the histological sections were stained using haematoxylin and eosin, Periodic acid-Schiff, picrosirius red and Masson's trichrome stains. The cytological samples were studied for stain quality, and the different cell types were counted. Histological examination was used to determine tissue types in the conjunctiva and their proportions. Analyses revealed a stratified squamous epithelium with some goblet cells and eventual pigmentation in the basal layer. Loose connective tissue with the presence of some mononuclear and polymorphonuclear cells was also observed. The epithelium of the maned wolf's bulbar conjunctiva resembles that of dogs and other carnivore species; furthermore, its physiological and pathological responses were similar to those of other carnivore species.

Ultrastructural analysis of the spermatogenesis in the guinea pig (Cavia porcellus)

Abstract: al for both, the establishment of appropriate management systems, and for the use of new species as animal models. In this study, we used light and electron microscopy to characterize the sexual development stages of the guinea pig (Cavia porcellus) in specimens of 30, 45 and 90 days of age. We observed the differentiation of spermatocytes only through transmission electron microscopy in the leptotene, zygotene and pachytene phases of meiosis, in 30-day-old animals. During puberty, there was differentiation of the germinative epithelium and formation of the acrosome. Spermatozoa, however, were not detected. Thus, we could infer that puberty happens after 45 days of age. Sexual maturity was evident in 90-day-old specimens. Our results showed that changes in the testicular germinative epithelium during the postnatal sexual development in guinea pig led to morphological changes, including the ones related to the development of Leydig and Sertoli cells, which are directly related to puberty. In this work, we provide new morphological subsidies for a better understanding of reproductive parameters of this species, enabling its use as an animal model in the field of the reproductive biology.