3D Tissue Scaffold Printing On Custom Artificial Bone Applications

Abstract

Production of defect-matching scaffolds is the most critical step in custom artificial bone applications. Three dimensional printing (3DP) is one of the best techniques particularly for custom designs on artificial bone applications because of the high controllability and design independency. Our long-term aim is to implant an artificial custom bone that is cultured with patient's own mesenchymal stem cells after determining defect architecture on patient's bone by using CT-scan and printing that defect-matching 3D scaffold with appropriate nontoxic materials. In this study, preliminary results of strength and cytotoxicity measurements of 3D printed scaffolds with modified calcium sulfate compositepowder (MCSCP) were presented. CAD designs were created and MCSCP were printed by a 3D printer (3DS, Visijet, PXL Core). Some samples were covered with salt solution in order to harden the samples. MCSCP and salt coated MCSCP were the two experimental groups in this study. Cytotoxicity and mechanical experiments were performed after surface examination withscanning electron microscope (SEM) and light microscope. Tension tests were performed for MCSCP and salt coated MCSCP samples. The 3D scaffolds were sterilized with ethylene oxide gas sterilizer, ventilated and conditioned with DMEM (10% FBS). L929 mouse fibroblast cells were cultured on scaffolds (3 repetitive) and cell viability was determined using MTT analysis. According to the mechanical results, the MCSCP group stands until average 71,305 N, while salt coated MCSCP group stands until 21,328N. Although the strength difference between two groups is statistically significant (p=0.001, Mann-Whitney U), elastic modulus is not (MCSCP=1,186Pa, salt coated MCSCP=1,169Pa, p=0.445). Cell viability (MTT analysis) results on day 1, 3, and 5 demonstrated thatscaffolds hadno toxic effect to the L929 mouse fibroblast cells. Consequently, 3D printed samples with MCSCP could potentially be a strong alternative (biocompatible) for current custom made scaffolds. Desired strength can be acquired with cell inoculation and cultivation of samples in a bioreactor for ossification

Keywords

• 3D Printing
• Artificial Bone
• Tissue Scaffold
• Biomechanics
• Tissue Engineering
• Biomedical Engineering

Kişiye Özel Yapay Kemik Uygulamaları için 3B Yazdırma Tekniği Kullanılarak Doku İskelesi Oluşturulması

Abstract

Kişiye özel yapay kemik uygulamalarında kritik basamak, defekte uygun iskelenin üretilmesidir. Tasarım özgürlüğü ve yüksek kontrol edilebilirlik nedeniyle, 3B yazdırma bilhassa kişiye özel uygulamalar için en uygun yöntemdir. Bu amaçla, 3B yazdırma tekniği kullanılarak mekanik özellikleri kemiğe uygun, toksik olmayan ve kemik doku oluşumunu destekleyecek iskele üretimi oldukça önemlidir. Uzun vadede hedefimiz CT taramayla hedef dokuda belirlenen defekte uygun geometride, uygun malzemeyle 3B iskele oluşturulması ve üzerine kişiden alınan mezankimal kök hücre ekilmesi ile oluşturulan nihai kemik dokunun hastaya aktarılmasıdır. Çalışmamızda, modifiye toz kompozit kullanılarak 3B yazdırılmış iskelelerin mukavemet sitotoksisite ölçümlerinin sonuçları sunulmuştur. Bilgisayarda oluşturduğumuz 3B tasarımlar, modifiye bir kompozit toz kullanılarak 3B yazıcı ile yazdırılmıştır. Örneklerin yarısı sertleştirmek için tuz çözeltisi ile kaplanıp kurutularak iki deney grubu oluşturulmuş, SEM ve ışık mikroskobu altında yüzey özellikleri incelendikten sonra sitotoksisite ve mekanik testleri yapılmıştır. Çekme testleri kontrol grubunda 6, tuzlu grupta 7 tekrarlı yapılmış, elastik modül hesaplanmıştır. Sitotoksisite için 3B iskeleler etilen oksit gaz sterilizatörüyle sterilizayona tabi tutulduktan sonra havalandırılmış ve DMEM (%10 FBS) ile şartlandırılmıştır. L929 fare fibroblast hücre hattı kullanılarak, iskelelere üç tekrarlı ekimler yapılmış ve MTT ile hücre canlılığı belirlenmiştir.
Mekanik test sonuçları incelendiğinde kontrol grubunun ortalama 71,305N'a (n=6) dayanabilmekte olduğu, tuzlu grubun ortalama 21,328N'a (n=7) dayanabilmekte olduğu gözlemlenmiştir. Her ne kadar dayanıklılık açısından istatistiksel olarak anlamlı bir fark bulunmuş (p=0,001, Mann-Whitney U) olsada, elastik modülleri arasındaki fark istatiksel olarak anlamlı bulunmamıştır (kontrol=1,186Pa, tuzlu=1,169Pa, p=0,445). MTT sonuçları incelendiğinde de her iki deney grubundaki iskele malzemelerinin toksik olmadığı, 1. 3. ve 5. gün analizlerine göre hücre canlılığının olumsuz etkilemediği görülmüştür. Dolayısıyla, modifiye toz ile 3B yazdırılmış numunelerin sitotoksik açıdan uygun olduğu (biyouyumlu) gözlemlenmiştir. Hedeflenen mukavemete kemik hücreleri ekimi ve numunenin biyoreaktörde kemikleştirilmesiyle ulaşılabileceği düşünülmektedir.  

Keywords

• 3B Yazdırma
• Yapay Kemik
• Doku İskelesi
• Biyomekanik

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