Category: General

Xenotransplantation. 2022 Sep 13:e12774. doi: 10.1111/xen.12774. Online ahead of print.

ABSTRACT

INTRODUCTION: Current bioprosthetic heart valve replacement options are limited by structural valvular deterioration (SVD) due to an immune response to the xenogenic scaffold. Autologous mesenchymal stem cell (MSC) recellularization is a method of concealing xenogenic scaffolds, preventing recipient immune recognition of xenogenic tissue heart valves, and potentially leading to reduction in SVD incidence. The purpose of this study is to examine the effects of autologous MSC recellularized tissue on the immune response of human whole blood to bovine pericardium (BP). We hypothesized that autologous MSC recellularization of BP will result in reduced pro-inflammatory cytokine production equivalent to autologous human pericardium.

METHODS: Bone marrow, human pericardium, and whole blood were collected from adult patients undergoing elective cardiac surgery. Decellularized BP underwent recellularization with autologous MSCs, followed by co-incubation with autologous whole blood. Immunohistochemical, microscopic, and quantitative immune analysis approaches were used.

RESULTS: We demonstrated that native BP, exposed to human whole blood, results in significant TNF-α and IL1β production. When decellularized BP is recellularized with autologous MSCs and exposed to whole blood, there is a significant reduction in TNF-α and IL1β production. Importantly, recellularized BP exposed to whole blood had similar production of TNF-α and IL1β when compared to autologous human pericardium exposed to human whole blood.

CONCLUSION: Our results suggest that preventing initial immune activation with autologous MSC recellularization may be an effective approach to decrease the recipient immune response, preventing recipient immune recognition of xenogeneic tissue engineered heart valves, and potentially leading to reduction in SVD incidence.

PMID:36098060 | DOI:10.1111/xen.12774

Braz J Cardiovasc Surg. 2022 Jun 8. doi: 10.21470/1678-9741-2020-0716. Online ahead of print.

ABSTRACT

INTRODUCTION: The aim of our study was to compare the primary closure (PRC) and patch angioplasty closure (PAC) of carotid artery following carotid endarterectomy (CEA).

METHODS: Data of patients who underwent CEA in the period from January 2005 to June 2020 were reviewed through files. Demographic characteristics, information about the operation, and postoperative follow-up outcomes of the patients were compared.

RESULTS: Of the 144 CEA cases included in the study, PRC and PAC were applied to 62 (43.7%) and 82 (56.3%) patients, respectively, for the carotid artery closure. Duration of surgery and carotid artery clamping time were not different between the PRC and PAC groups (106.73±17.13 minutes vs. 110.48±20.67 minutes, P=0.635; 24.25±11.56 minutes vs. 25.19±8.99 minutes, P=0.351, respectively). Postoperative respiratory impairment was more common in the PRC group (P=0.012); however, nerve injuries (P=0.254), surgical wound hematomas (P=0.605), surgical site infections (P=0.679), and mortality (P=0.812) were not significantly different between the groups. During the mean patient follow-up time of 26.13±19.32 months, restenosis was more common in the PRC group than in the PAC group (n=26, 41.9% vs. n=4, 4.9%, respectively; P=0.003). Frequencies of stroke (n=4, 2.8% vs. n=2, 2.4%, respectively; P=0.679), transient ischemic attacks (n=2, 1.4% vs. n=0, 0%, respectively; P=0.431), and mortality (n=4, 6.5% vs. n=4, 4.9%, respectively; P=0.580) were not significantly different between the PRC and PAC groups.

CONCLUSION: We are of the opinion that the PAC method is effective and safe for carotid artery closure in patients undergoing CEA.

PMID:35675495 | DOI:10.21470/1678-9741-2020-0716

Acta Biomater. 2022 Oct 15;152:113-123. doi: 10.1016/j.actbio.2022.08.057. Epub 2022 Aug 30.

ABSTRACT

Chemically crosslinked acellular bovine pericardium (ABP) has been widely used in clinical practice as bioprostheses. To ensure its consistency and durability, crosslinkers are used in excess, with stability guided by indicators including the hydrothermal denaturation temperature, the enzymatic resistance and the degree of crosslinking. Yet, understanding of the intermolecular structure in collagen fibrils which imparts the intrinsic stability of the ABPs is lacking, and the discrepancies in the stability criteria in varied conditions are poorly explained. In this study, synchrotron small-angle X-ray scattering (SAXS) in combination with thermal and colorimetric methods are employed to investigate the changes in the structure and the stability of ABPs during crosslinking using glutaraldehyde (GA) or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) at different concentrations. Based on the findings, a mechanism is proposed to explicate the crosslinking effects on collagen structure and the relationship between the structure and each stability indicator. At low crosslinker concentrations, the telopeptidyl-helical linkages are preferred, which cause rearrangements in the intermolecular structure of collagen, and efficiently contribute to its stabilities. Excess crosslinking is revealed by a revert trend in structural changes and the plateauing of the stabilities, assigning to the helical-helical linkages and monovalent bindings. The former would improve thermal stability but not collagenase resistance, whereas the latter have negligible effects. Overall, this study provides a mechanistic understanding of the chemical crosslinking of ABPs, which will contribute to the future development of more efficient and economically viable strategies to produce bioprostheses. STATEMENT OF SIGNIFICANCE: Chemical crosslinking imparts suitable properties to acellular bovine pericardium (ABP) for clinical applications, yet the understanding is lacking on the structure-stability relationship especially under different crosslinking conditions. Structural evidence in this study differentiates the binding sites during crosslinking in collagen fibrils at different crosslinker concentrations, highlighting the excess usage in the conventional crosslinking treatments. The mechanism based on the structure of collagen also successfully explains the dissimilarity in hydrothermal and enzymatic stabilities with varied crosslinking conditions. Future researches focusing on developing biomaterials via chemical crosslinking of ABPs would benefit from this study, for its contribution to the better understanding of the relationship of collagen structure and functions.

PMID:36049624 | DOI:10.1016/j.actbio.2022.08.057