연골재생을 위한 다당류 기반 주입형 하이드로젤

Abstract

For cartilage regeneration via tissue engineering approaches, isolated chondrocytes need to be applied as a form of cell/scaffold construct. Hyaluronate, which is known for its exceptional biocompatibility and chondrogenic performance, has been often used as a scaffold for cartilage regeneration. Typical hyaluronate hydrogels require excipient chemical cross-linking reagents to form hydrogels, which may induce acute or chronic side toxic effects. In this thesis, hyaluronate-based hydrogels were prepared using only natural polysaccharides without using additional cross-linking molecules. Hyaluronate was partially oxidized with sodium periodate to generate aldehyde groups to the hyaluronate backbone. Hydrogels were prepared under physiological conditions by simply mixing solutions of oxidized hyaluronate and glycol chitosan via Schiff base formation between aldehyde groups in oxidized hyaluronate and amino groups in glycol chitosan. Various characteristics of hyaluronate/glycol chitosan hydrogels were investigated in vitro. The degree of oxidization, polymer concentration, as well as hyaluronate/glycol chitosan composition ratio were important to regulate the mechanical properties of the gels. Degradation kinetics of oxidized hyaluronate/glycol chitosan gels were also investigated in vitro. Interestingly, these hydrogels showed self-healing behavior when combined with adipic acid dihydrazide. Repeated self-healing features were investigated in microscopic and macroscopic measurements. Hyaluroante-based hydrogels developed in this thesis showed good biocompatibility. This approach may be potentially useful in the design of an injectable system for many tissue engineering applications.|연골재생을 위해 조직공학에서는 채취한 연골세포를 세포/지지체 혼합물의 형태로 인체에 전달한다. 지지체로 이용되는 생체재료들 중에서 히알루론산은 연골재생능이 매우 탁월하여 연골치료 및 재생에 자주 이용된다. 기존의 히알루론산 기반 하이드로젤은 가교를 위하여 화학물을 첨가하는데, 이는 급성 또는 만성 부작용의 우려가 있었다. 이 논문에서는 추가적인 화학가교제 없이 오직 천연물에서 유래한 다당류만으로 히알루론산 기반 하이드로젤을 제조하였다. 우선 산화과정을 통하여 히알루론산에 알데히드 그룹을 도입하였다. 하이드로젤은 산화 히알루론산 용액과 글리콜 키토산 용액의 혼합만으로 제조가 가능한데, 산화된 히알루론산의 알데히드 그룹과 글리콜 키토산의 아민 그룹이 생리환경조건에서 반응하여 Schiff 염기 반응을 일으켜 가교구조를 형성하였다. 히알루론산/글리콜 키토산 하이드로젤의 다양한 특징들을 분석하기 위해 화학적인 분석 및 유변학적 측정방법들이 시행되었다. 실험결과에 의하면 히알루론산과 글리콜 키토산의 비율뿐만 아니라 산화도 및 고분자의 농도가 젤의 물성을 조절하는데 중요한 요소임을 알아내었다. 또한 하이드로젤의 생리식염수 내에서의 분해성도 측정하였다. 추가적으로 아디프산의 첨가는 산화 히알루론/글리콜 키토산 하이드로젤에 가역적이고 반복적인 자가치유 기능을 부여하고 이것을 거시적 또는 미시적으로 확인할 수 있었다. 그리고 ATDC5 연골세포를 이용한 생체 외 실험을 통하여 이러한 하이드로젤은 연골재생에 적합한 생체친화성을 가지고 있음을 확인할 수 있었다. 이러한 연구결과들은 조직공학, 특히 연골재생 분야에 있어 유용한 방안을 제공해 줄 수 있을 것으로 기대된다.; For cartilage regeneration via tissue engineering approaches, isolated chondrocytes need to be applied as a form of cell/scaffold construct. Hyaluronate, which is known for its exceptional biocompatibility and chondrogenic performance, has been often used as a scaffold for cartilage regeneration. Typical hyaluronate hydrogels require excipient chemical cross-linking reagents to form hydrogels, which may induce acute or chronic side toxic effects. In this thesis, hyaluronate-based hydrogels were prepared using only natural polysaccharides without using additional cross-linking molecules. Hyaluronate was partially oxidized with sodium periodate to generate aldehyde groups to the hyaluronate backbone. Hydrogels were prepared under physiological conditions by simply mixing solutions of oxidized hyaluronate and glycol chitosan via Schiff base formation between aldehyde groups in oxidized hyaluronate and amino groups in glycol chitosan. Various characteristics of hyaluronate/glycol chitosan hydrogels were investigated in vitro. The degree of oxidization, polymer concentration, as well as hyaluronate/glycol chitosan composition ratio were important to regulate the mechanical properties of the gels. Degradation kinetics of oxidized hyaluronate/glycol chitosan gels were also investigated in vitro. Interestingly, these hydrogels showed self-healing behavior when combined with adipic acid dihydrazide. Repeated self-healing features were investigated in microscopic and macroscopic measurements. Hyaluroante-based hydrogels developed in this thesis showed good biocompatibility. This approach may be potentially useful in the design of an injectable system for many tissue engineering applications.