Development of macroporous bioceramic materials based on multi-ion doped calcium-hydroxyapatite coated with chitosan

In recent years, scientists have been working on developing biocompatible materials that closely mimic the structure and properties of natural biological tissues for their application in hard tissue regeneration and controlled drug release. Human bones and teeth primarily consist of calcium-phosphate crystals with small amounts of various ions incorporated into their crystal structure. The aim of this study was to examine the possibility of processing macroporous bioceramic scaffolds based on calcium-hydroxyapatite (HAp) doped with magnesium (Mg), strontium (Sr) and fluorine (F) ions, subsequently coated with polymer chitosan. In this study, the doped HAp powder was synthesized by a hydrothermal process, and scaffolds were made using the sponge replica method, sintered and then coated with the chitosan. The influence of dopant ions and chitosan on the scaffold's microstructure, mechanical properties, bioactivity, cytotoxicity and drug release properties was examined. Energy dispersive spectroscopy confirmed that Mg and Sr are incorporated in all powder samples, while the presence of F was confirmed in samples synthesized with 1 and 2 mol.% F in the precursor solution. The phase composition of powders and scaffolds determined by X-ray analysis showed the presence of HAp and β-tricalcium phosphate phase (β-TCP) in scaffolds. In the compressive strength (CS) test, coated scaffolds showed significantly higher CS compared to uncoated scaffolds. Scanning electron microscopy was used to examine the morphology of nanostructured powders, microstructure, and the bioactivity of the scaffolds. The uncoated scaffolds showed satisfactory bioactivity after being immersed in simulated body fluid for 28 days, while lower bioactivity was observed in the coated scaffolds due to the slow degradation of chitosan. The synthesized scaffolds also demonstrated to have a positive impact on cell viability, even slightly stimulating the cell proliferation. Additionally, scaffolds were shown to successfully release drug. In concusion, the addition of ions and chitosan polymer significantly improved the properties of the obtained scaffolds, which indicates their potential application in tissue engineering and controlled drug release.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Association of Bax expression and Bcl2/Bax ratio with clinical and molecular prognostic markers in chronic lymphocytic leukemia

Uvod: Rezistencija na apoptozu koja karakteriše maligne B limfocite in vivo u hroničnoj limfocitnoj leukemiji (HLL) delimično je uzrokovana unutrašnjim poremecajima apoptotske mašinerije u ovim celijama. Ti poremecaji su rezultat genetičkih promena i aberantne ekspresije regulatora procesa apoptoze, među kojima ključnu ulogu imaju članovi Bcl2 familije. Cilj: Cilj ove studije je bio da se ispita udruženost nivoa ekspresije proapoptotskog Bax gena, kao i Bcl2/Bax odnosa, sa kliničkim karakteristikama bolesnika sa HLL kao i molekularnim prognostičkim markerima, i to mutacionim statusom rearanžiranih gena za teške lance imunoglobulina (IGHV) i ekspresijom gena za lipoproteinsku lipazu (LPL). Metode: Analizirana je ekspresija Bax iRNK i Bcl2/Bax iRNK odnos u mononuklearnim celijama periferne krvi 58 bolesnika sa HLL i 10 zdravih kontrola metodom reverzne transkripcije i lančane reakcije polimeraze u realnom vremenu (qRT-PCR). Rezultati: Detektovana je povišena ekspresija Bax gena u HLL uzorcima u odnosu na kontrolne uzorke (p=0,003), kao i povišen Bcl2/Bax odnos (p= lt 0,001). Kada je u pitanju udruženost sa prognostičkim markerima, Bcl2/Bax odnos je ispoljio negativnu korelaciju sa vremenom udvostručavanja broja limfocita (r=-0,307; p=0,0451), dok je visoka ekspresija Bax bila povezana sa LPL-pozitivnim statusom (p=0,035). I ekspresija Bax gena i Bcl2/Bax odnos su bili viši kod bolesnika sa nemutiranim u odnosu na bolesnike sa mutiranim IGHV genima, ali nije dostignuta statistička značajnost. Zaključak: Rezultati ove studije ukazuju na mogucu ulogu poremecene ekspresije Bcl2 i Bax gena, koja dovodi do visokog Bcl2/Bax odnosa u leukemijskim celijama, u patogenezi i kliničkom toku HLL.Background: In chronic lymphocytic leukemia (CLL), in vivo apoptotic resistance of malignant B lymphocytes results, in part, from the intrinsic defects of their apoptotic machinery. These include genetic alterations and aberrant expression of many apoptosis regulators, among which the Bcl2 family members play a central role. Aim: The aim of this study was to investigate the association of pro-apoptotic Bax gene expression and Bcl2/Bax ratio with the clinical features of CLL patients as well as with molecular prognostic markers, namely the mutational status of rearranged immunoglobulin heavy variable (IGHV) genes and lipoprotein lipase (LPL) gene expression. Methods: We analyzed the expression of Bax mRNA and Bcl2/Bax mRNA ratio in the peripheral blood mononuclear cells of 58 unselected CLL patients and 10 healthy controls by the quantitative reverse-transcriptase polymerase chain reaction. Results: We detected significant Bax gene overexpression in CLL samples compared to non-leukemic samples (p=0.003), as well as an elevated Bcl2/Bax ratio (p= lt 0.001). Regarding the association with prognostic markers, the Bcl2/Bax ratio showed a negative correlation to lymphocyte doubling time (r=-0.307; p=0.0451), while high-level Bax expression was associated with LPL-positive status (p=0.035). Both the expression of Bax and Bcl2/Bax ratio were higher in patients with unmutated vs. mutated IGHV rearrangements, but this difference did not reach statistical significance. Conclusions: Our results suggest that dysregulated expression of Bcl2 and Bax, which leads to a high Bcl2/Bax ratio in leukemic cells, contributes to the pathogenesis and clinical course of CLL

Expression of the Bcl2 gene in chronic lymphocytic leukaemia patients

Hronična limfocitna leukemija (HLL) se manifestuje kao klonska ekspanzija zrelih B limfocita, čija se akumulacija pripisuje prvenstveno poremećajima procesa apoptoze. U HLL su uočene genetičke promene i aberantna ekspresija različitih članova Bcl2 genske familije, koji imaju ključnu ulogu u regulaciji unutrašnjeg, mitohondrijskog puta aktivacije apoptoze. U ovom radu je analizirana ekspresija anti-apoptotskog Bcl2 gena u grupi od 58 pacijenata obolelih od HLL. Metodom kvantitativnog RT-PCRa detektovana je povišena ekspresija Bcl2 mRNA u HLL uzorcima u odnosu na kontrolne uzorke (p= lt 0.001). 'Receiver operating characteristic' (ROC) analiza je pokazala da nivo ekspresije Bcl2 ima visoku moć diskriminacije između pacijenata i zdravih kontrola (A=0.98, 95% CI=0.95-1.009, p lt 0.0001).Chronic lymphocytic leukaemia (CLL) manifests as clonal expansion of mature B lymphocytes, whose accumulation is primarily attributed to the dysregulation of apoptosis. Aberrant expression, as well as genetic alterations within various Bcl2 family members and central regulators of the intrinsic, mitochondriamediated apoptotic pathway all hasve been observed in CLL. Here, we report the expression analysis of the anti-apoptotic Bcl2 gene in a cohort of 58 CLL patients. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) analysis revealed a significant overexpression of Bcl2 mRNA in CLL samples compared to control samples (p= lt 0.001). Receiver operating characteristic (ROC) analysis showed that the level of Bcl2 expression exerts a high discriminatory power between patients and healthy subjects (A=0.98, 95% CI=0.95-1.009, p lt 0.0001)