Raimondas Sirmenis

Micro-structured polymer scaffolds fabricated by direct laser writing for tissue engineering

This work presents the latest results on direct laser writing of polymeric materials for tissue engineering applications. A femtosecond Yb:KGW laser (300 fs, 200 kHz, 515 nm) was used as a light source for non-linear lithography. Fabrication was implemented in various photosensitive polymeric materials, such as: hybrid organic-inorganic sol-gel based on silicon-zirconium oxides, commercial ORMOCER® class photoresins. These materials were structured via multi-photon polymerization technique with submicron resolution. Porous three-dimensional scaffolds for artificial tissue engineering were fabricated with constructed system and were up to several millimeters in overall size with 10 to 100 μm internal pores. Biocompatibility of the used materials was tested in primary rabbit muscle-derived stem cell culture in vitro and using laboratory rats in vivo. This interdisciplinary study suggests that proposed technique and materials are suitable for tissue engineering applications.

Large Scale Laser Two-Photon Polymerization Structuring for Fabrication of Artificial Polymeric Scaffolds for Regenerative Medicine

We present a femtosecond Laser Two‐Photon Polymerization (LTPP) system of large scale three‐dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub‐micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY—ALS130‐100, Z—ALS130‐50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three‐dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three‐dimensional) structures. An illumination system and CMOS camera enables online process monitoring. Control of all equipment is automated via custom made computer software “3D‐Poli” specially designed for LTPP applications. Structures can be imported from computer aided design STereoLihography (stl) files or programmed directly. It can be used for rapid LTPP structuring in various photopolymers (SZ2080, AKRE19, PEG‐DA‐258) which are known to be suitable for bio‐applications. Microstructured scaffolds can be produced on different substrates like glass, plastic and metal. In this paper, we present microfabricated polymeric scaffolds over a large area and growing of adult rabbit myogenic stem cells on them. Obtained results show the polymeric scaffolds to be applicable for cell growth practice. It exhibit potential to use it for artificial pericardium in the experimental model in the future.We present a femtosecond Laser Two‐Photon Polymerization (LTPP) system of large scale three‐dimensional structuring for applications in tissue engineering. The direct laser writing system enables fabrication of artificial polymeric scaffolds over a large area (up to cm in lateral size) with sub‐micrometer resolution which could find practical applications in biomedicine and surgery. Yb:KGW femtosecond laser oscillator (Pharos, Light Conversion. Co. Ltd.) is used as an irradiation source (75 fs, 515 nm (frequency doubled), 80 MHz). The sample is mounted on wide range linear motor driven stages having 10 nm sample positioning resolution (XY—ALS130‐100, Z—ALS130‐50, Aerotech, Inc.). These stages guarantee an overall travelling range of 100 mm into X and Y directions and 50 mm in Z direction and support the linear scanning speed up to 300 mm/s. By moving the sample three‐dimensionally the position of laser focus in the photopolymer is changed and one is able to write complex 3D (three‐dimensional) structures....

FBN1 polymorphisms in patients with the dilatative pathology of the ascending thoracic aorta

OBJECTIVES To investigate polymorphisms of the fibrillin-1 (FBN1) gene (namely, rs2118181, rs1036477, rs10519177, rs755251 and rs4774517) in a case-control study for dilatative pathology of the ascending thoracic aorta (DPATA) from Lithuanians. METHODS We studied 312 patients who had undergone aortic reconstructive surgery for DPATA. These patients were sub-divided according to the phenotypes of their DPATA into (i) ascending aortic aneurysm (n = 160), (ii) post-stenotic dilatation of the ascending aorta due to aortic valve stenosis (n = 79) and (iii) Stanford A dissection (n = 73). The reference group (n = 472) was recruited from a random sample screened within epidemiological studies of the Lithuanian population. FBN1 polymorphisms were studied by real-time polymerase-chain-reaction amplification. RESULTS Patients within the aortic dissection sub-group had significantly higher minor allele frequencies in all five FBN1 single nucleotide polymorphism (SNPs) studied versus reference group subjects (P < 0.0001). Minor allele frequencies in SNPs rs2118181, rs1036477 were significantly higher in those with aortic aneurysm when compared with the reference group (P = 0.007). Thus, minor alleles of FBN1 SNPs studied were significantly associated with aortic dissection with odds ratios (ORs) 2.59-2.13, P < 0.001, while SNPs rs2118181 and rs1036477 with an increased risk of ascending aortic aneurysm [OR 1.67, confidence interval (CI) 95% 1.61-2.40]. The association of FBN1 genotypes with each phenotype of DPATA was assessed using logistic regression models adjusted for gender, age and hypertension. The additive model best fitted SNPs rs2118181 and rs1036477 in association with the ascending aortic aneurysm sub-group (OR 1.70, CI 95% 1.17-2.46) or the Stanford A dissection sub-group (OR 2.64, CI 95% 1.66-4.19). A recessive model fitted best the association between SNPs rs10519177, rs755251, rs4774517 and Stanford A dissection (OR 4.31, CI 95% 2.06-9.01). There were no significant associations between all studied FBN1 SNPs and post-stenotic or bicuspid aortic dilatation. CONCLUSIONS Our study provides evidence for the following: (i) FBN1 SNPs rs2118181, rs1036477, rs10519177, rs4774517, rs755251 may increase susceptibility to aortic dissections and (ii) FBN1 SNPs rs2118181, rs1036477 to the formation of aortic aneurysms. Thus, these SNPs might be considered as biomarkers for identifying patients at risk for ascending aortic aneurysm and aortic dissection.

Surgical correction of atrial septal defect in the elderly

Introduction Atrial septal defects (ASDs) are one of the most common congenital malformations in adults. Correction of ASDs in advanced age remains controversial, even though beneficial effects in this patient group were found in recent studies. In older patients, less invasive transcatheter closure of ASDs has been recommended. Aim The aim of this study was to analyze our advanced age ASD surgical cohort: early and late results. Material and methods Retrospective analysis of 32 patients operated on at an age of ≥ 60 years (i.e. age 66.13 ± 4.8, range from 60 to 78) in our center between 2001 and 2011 was carried out. We reviewed our experience of surgical ASD closure in elderly patients over a 10-year period to assess the effects of this type of treatment on early postoperative and long-term survival, early and late complications, preoperative and postoperative clinical status (New York Heart Association [NYHA] functional class), pulmonary hypertension (PH) and atrial arrhythmias. The patients were divided into two groups according to age. Results The frequency of comorbidities was lower in younger age group patients (11 [61%] vs. 13 [93%], p < 0.05). Atrial fibrillation/flutter was found in 21 (66%) of all patients. Late postoperative mortality was higher in the older patient group (3 [21%] vs. 1 [5.6%]). Despite this, we observed significant improvement of symptoms and functional ability in the older population after surgical ASD closure (group I, n = 10 [56%] vs. group II, n = 12 [86%]). Conclusions Surgical correction of clinically significant ASD is effective even in older patients with comorbidities.

Laser microstructured 3D polymeric biocompatible implants

In this report we present experimental results on biocompatibility based on stem cell growth experiments in vitro as well as reaction of living organism to polymer implants in vivo of femtosecond laser 3D micro/nanostructurable photopolymers. A synergetic study on materials for rapid 3D scaffold fabrication having micrometer features and being centimeter in size, their biocompatibility in vitro and in vivo was done. The systematic study was performed providing consistent information which is important for further progress in cell growth and tissue engineering experiments. The chosen materials where of four different classes: well known biocompatible hybrid ORMOCER (Ormocore b59, Micro Resist) [1], widely used biodegradable di-acrylated poly(ethylene)glycol (PEG-DA-258, Sigma-Aldrich) [2], pure acrylate AKRE (SR368, Sartomer) [3] and novel high quality laser structurable material ORMOSIL (SZ2080, FORTH) [4]. All of the materials were evaluated by their suitability for femtosecond laser structuring, which is well established as a technique enabling rapid and flexible production of 3D micro/nanostructures. All photopolymers could be 3D structured with &#60; 1 µm resolution and up to cm in overall sizes, thus materializing the computer models of the scaffolds with required pore sizes and porosities. The typical dimensions of scaffolds were 5 × 5 × 0.5 mm3 discs with 25 µm pore sizes and 40–60% porosity.

Ligonių, sergančių išemine kardiomiopatija, gyvenimo kokybės ir fizinio pajėgumo palyginimas

Julius Treideris 1 , Rimantas Karalius 1 , Raimondas Sirmenis 2 , Gražina Luksaitė 2 , Vytautas Lastas 2 , Eugenijus Kosinskas 1 , Arnoldas Pranckietis 2 , Vytautas Sirvydis 1 1 Vilniaus universiteto Sirdies chirurgijos centras, Santariskių g. 2, LT-08661 Vilnius 2 Vilniaus universiteto ligoninės Santariskių klinikų Sirdies chirrugijos centras, Santariskių g. 2, LT-08661 Vilnius El pastas: julius.t@mail.lt Įvadas / tikslas Dauguma autorių savo tyrimuose nagrinėja kairiojo skilvelio funkcijos atsikūrimo ir ligonių isgyvenimo problemas po aortos vainikinių arterijų jungcių operacijų ir perkutaninės transluminalinės vainikinių arterijų angioplastikos, taciau mažai atsižvelgiama į ligonių gyvenimo kokybės ir fizinio pajėgumo pagerėjimą. Tyrimo tikslas – Istirti ligonių, sergancių isemine kardiomiopatija, kuriems sumažėjusi kairiojo skilvelio isvarymo frakcija, gyvenimo kokybe ir fizinį pajėgumą po aortos vainikinių arterijų jungcių operacijų ir perkutaninės transluminalinės vainikinių arterijų angioplastikos. Ligoniai ir metodai Atliktas klinikinis 40 ligonių, kuriems koronarografijos metu buvo aptiktas priekinės tarpskilvelinės sakos užsikimsimas ir kad sumažėjusi kairiojo skilvelio isvarymo frakcija, esant gyvybingam miokardui, stebėjimas. Ligoniai buvo suskirstyti į 3 grupes: analizuojamoje I grupėje buvo 13 ligonių, kurių amžiaus vidurkis buvo 67,6 ± 3,97 metų, moterų ir vyrų santykis – 23,1 ir 76,9%. Siems ligoniams buvo daryta aortos vainikinių arterijų jungcių operacija. Analizuojamoje II grupėje buvo 7 ligoniai, kurių amžiaus vidurkis 65,7 ± 2,06 metų, moterų ir vyrų santykis 28,6 ir 71,4%. Siems ligoniams buvo atlikta perkutaninė transluminalinė vainikinių arterijų angioplastika. Analizuojamoje III grupėje buvo 20 ligonių, kurių amžiaus vidurkis buvo 67,6 ± 4,11 metų, moterų ir vyrų santykis – 65 ir 35%. Sie ligoniai buvo gydyti konservatyviai. Ligoniams buvo atlikti tyrimai: pildyta Minesotos universiteto anketa „Gyvenimas sergant sirdies nepakankamumu“, sesių minucių trukmės ėjimo testas, sirdies echoskopija, veloergometrija, natriuretinio peptido tyrimas. Rezultatai Palyginus sias tris ligonių grupes matyti, kad I ir II grupės ligonių gyvenimo kokybė, echoskopiniai kairiojo skilvelio duomenys, fizinis pajėgumas po 24 savaicių yra geresni negu III grupės ligonių. Po 24 savaicių I ir II grupės ligoniai per 6 min. nuėjo atitinkamai 442,6 ± 1,68 ir 498,6 ± 1,58 metro, kas atitinka I funkcine klase pagal NYHA, o III grupės ligoniai nuėjo 375,6 ± 174 metrus – o tai atitinka II funkcine klase pagal NYHA. Po 24 savaicių I ir II grupės ligonių kraujo plazmoje ryskiai sumažėjo natriuretinio peptido koncentracija – atitinkamai NT-proBNP 146,6 ± 3,2 ir 138,5 ± 3,13 pg/ml, palyginti su III grupės ligoniais, kurių NT-proBNP 298,6 ± 3,12 pg/ml (p 0,0062) ir nedaug padidėjo III grupės ligoniams (nuo 66 ± 4,8 iki 67 ± 5,1 mm) (p > 0,0056). Po 24 savaicių I ir II grupės ligonių bendras atliktas veloergometrijos metu darbas buvo daug geresnis (atitinkamai 72,8 ± 5,2 ir 78,6 ± 4,9 kJ) negu III grupės ligonių 63,8 ± 8,2 kJ (p < 0,023). Isvados Ligonių, kuriems aortos vainikinių arterijų jungtimis ar perkutaninės transluminalinės vainikinių arterijų angioplastikos metu revaskuliarizuotas priblokstas gyvybingas miokardas, gyvenimo kokybė ir fizinis pajėgumas atokiuoju laikotarpiu yra geresni negu ligonių, gydytų konservatyviai. Ligonių po perkutaninės transluminalinės vainikinių arterijų angioplastikos gyvenimo kokybė ir fizinis pajėgumas atsikuria greiciau negu po aortos vainikinių arterijų jungcių operacijos. Tai paiskinama tuo, kad dirbtinės kraujo apytakos sąlygomis atlikta aorto vainikinių arterijų jungcių operacija ūmiuoju laikotarpiu pablogina miokardo būkle. Kairiojo skilvelio remodialiacija vyksta tik revaskuliarizavus miokardo infarktą. Konservatyvaus gydymo metu toliau vystosi kairiojo skilvelio diliatacija. Pagrindiniai žodžiai: sirdies nepakankamumas, iseminė kardiomiopatija, gyvenimo kokybė Comparison of quality of life and physical condition of heart failure Julius Treideris 1 , Rimantas Karalius 1 , Raimondas Sirmenis 2 , Gražina Luksaitė 2 , Vytautas Lastas 2 , Eugenijus Kosinskas 1 , Arnoldas Pranckietis 2 , Vytautas Sirvydis 1 1 Cardiac Surgery Centre, Vilnius University, Santariskių str. 2, LT-08661 Vilnius, Lithuania 2 Cardiac Surgery Centre of Vilnius University Hospital „Santariskių klinikos“, Santariskių str. 2, LT-08661 Vilnius, Lithuania E-mail: julius.t@mail.lt Background / objective The survival of patients and recovery of the left ventricle function after coronary artery by-pass grafting and percutaneous transluminar angioplasty are widely analysed; however, changes in the quality of life and physical condition are given less attention. The aim of the study was to evaluate the quality of life and physical condition after coronary artery by-pass grafting and percutaneous transluminar angioplasty in patients with a decreased left ventricle ejection fraction suffering from heart failure. Patients and methods The study involved 40 patients with viable myocardium, who showed occlusion of the anterior interventricular artery and a decreased left ventricle ejection fraction on coronarography. Group 1 of patients included 13 subjects (mean age, 67.6 ± 3.97 years, female / male ratio 28.6% vs 71.4%) after coronary artery by-pass grafting; group 2 included 7 patients after percutaneous transluminar angioplasty (mean age, 65.7 ± 2.06 years, female / male ratio 23.1% vs 76.6%), and group 3 consisted of 20 patients who were treated conservatively (mean age, 67.6 ± 4.11 years, female / male ratio 65% vs 35%). The patients were evaluated using the Minnesota University Living with Heart Questionnaire, they underwent a six-minute walking, echocardioscopy, veloergometry, natriuretic peptide tests. Results A comparison of data in these groups after 24 weeks showed a greater improvement of quality of life, echoscopic findings of the left ventricle, and physical condition in groups 1 and 2. The 6-minute walking distance after 24 weeks in groups 1 and 2 were 442.6 ± 1.68 and 498.6 ± 1.58 m, respectively, corresponding to NYHA functional class I; the walking distance in group 3 was 375.6 ± 174 meters (NYHA functional class II). Patients in groups 1 and 2 after 24 weeks showed a marked decrease of natriuretic peptide plasma levels (NT-proBNP 146.6 ± 3.2 and 138.5 ± 3.13 pg/ml, respectively) in comparison with that of group 3 (NT-proBNP 298.6 ± 3.12 pg/ml) (p 0.0062) and slightly decreased in group 3 (from 66 ± 4.8 to 67 ± 5.1 mm) (p > 0.0056). The workload after 24 weeks on a veloergometer was markedly higher in groups 1 and 2 (72.8 ± 5.2 and 78.6 ± 4.9 kJ, respectively) in comparison with that of group 3 (63.8 ± 8.2 kJ) (p < 0.023). Conclusions The patients who underwent revascularization of stunned myocardium by means of coronary artery bypass grafting or percutaneous transluminar angioplasty, at late follow-up showed a better quality of life and physical condition in comparison with these of patients who were treated conservatively. The recovery of quality of life and physical conditions was faster in the group of patients after percutaneous transluminar coronary artery angioplasty. This phenomenon may be explained by the fact that coronary artery bypass grafting performed under cardiopulmonary bypass worsens the myocardium condition in the acute period. The remodelling of the left ventricle develops after revascularization of myocardial infarction. The dilation of the left ventricle undergoes the further development during the conservative treatment. Key words: heart failure, ischemic cardiomyopathy, quality of life