• Journal of Periodontal and Implant Science
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• 제43권6호
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• pp.251-261
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• 2013

A paradigm shift is taking place in medicine and dentistry from using synthetic implants and tissue grafts to a tissue engineering approach that uses degradable porous three-dimensional (3D) material hydrogels integrated with cells and bioactive factors to regenerate tissues such as dental bone and other oral tissues. Hydrogels have been established as a biomaterial of choice for many years, as they offer diverse properties that make them ideal in regenerative medicine, including dental applications. Being highly biocompatible and similar to native extracellular matrix, hydrogels have emerged as ideal candidates in the design of 3D scaffolds for tissue regeneration and drug delivery applications. However, precise control over hydrogel properties, such as porosity, pore size, and pore interconnectivity, remains a challenge. Traditional techniques for creating conventional crosslinked polymers have demonstrated limited success in the formation of hydrogels with large pore size, thus limiting cellular infiltration, tissue ingrowth, vascularization, and matrix mineralization (in the case of bone) of tissue-engineered constructs. Emerging technologies have demonstrated the ability to control microarchitectural features in hydrogels such as the creation of large pore size, porosity, and pore interconnectivity, thus allowing the creation of engineered hydrogel scaffolds with a structure and function closely mimicking native tissues. In this review, we explore the various technologies available for the preparation of macroporous scaffolds and their potential applications.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권6호
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• pp.374-378
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• 2003

Aim : Several injectable materials have been used in the application of osteogenic bone substitute; however, nothing has won universal acceptance. This study was performed to investigate whether chitosan-alginate gel/MSCs/BMP-2 composites are potentially injectable materials for new bone formation. Material and Methods : The composites were injected into the subcutaneous space on the dorsum of the nude mouse to investigate whether new bone would be tissue engineered in the mouse. The composites were examined histologically over a 12-week period. Results : The composites implanted in the mouse were able to tissue engineer new bone, and the newly formed bone consisted of trabecular bone and calcified bone matrix. Conclusions : The present study shows that chitosan-alginate gel/MSCs/BMP-2 composites have the potential to become real injectable materials for new bone formation.

• 폴리머
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• 제27권3호
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• pp.226-234
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• 2003

이프리플라본은 이소플라본의 파생물로서 골의 재흡수를 방지하여 골의 재형성을 방해함으로써 골 형성에 도움을 준다. 이프리플라본은 칼슘의 양을 안정적으로 증가시킴과 함께 골수 줄기 세포의 작용으로 세포층에 칼슘을 침착시킨다. 조직공학적 골을 형성시키기 위해 락타이드-글리를라이드 공중합체 (PLGA)에 이프리플라본을 함유시킨 지치체를 용매 캐스팅/염 추출법으로 제조하였다. 수은 다공도계, 주사 전자 현미경, 시차 주사 열량계, X선 회절기를 이용하여 특성결정을 수행하였고, 이프리플라본이 함유된 지지체와 이프리플라본이 함유되지 않은 지지체를 면역이 결핍된 쥐의 피하에 삽입하여 이들의 골 형성을 비교하였다. 조직을 hematoxylin & eosin, 본쿠사 염색과 면역화학적 염색법인 콜라겐 I 형과 오스테오칼신 염색을 하였다. 이프리플라본이 함유된 담체의 다공도는 91.7% 이상이었고, 평균 다공 크기도 101 $\mu\textrm{m}$였다. PLGA로만 제조된 지지체와 이프리플라본을 50% 함유시킨 지지체를 동물 실험을 수행한 결과 이프리플라본은 피하 층과 다른 연조직에서 미분화 줄기 세포가 칼슘 침착, 골아 세포, 골상으로의 유도에 더 많은 영향을 주는 것을 관찰하였다. 결론적으로 이프리플라본을 함유한 지지체에서 이프리플라본이 골형성에 중요한 요인으로 작용한다고 사료된다.

• Journal of Chest Surgery
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• 제37권3호
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• pp.220-227
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• 2004

관상동맥 질환과 말초혈관 질환의 증가에 따라 직경 6 mm 이하의 소구경 혈관의 필요성이 증가하고 있다. 저자들은 조직공학적 방법을 이용하여 소구경 인공혈관을 제작하여 생체 실험을 시행하였다. 동종 판막을 얻어 이를 탈세포화시킨 후 피실험동물의 골수를 채취하여 탈세포화시킨 혈관용 지지체(scaffold) 위에 이식하였다. 이와 같이 하여 제작된 인공 혈관을 잡견의 양측 경동맥에 이식한 후 혈관이 막히거나, 8주가 되었을 때 이를 제거하여 조직학적 검사를 시행하였다. 자가 세포를 이식하지 않고 지지체만을 이식하였던 대조군 4마리 중 3마리의 혈관은 2주 이내에 모두 막힌 것을 확인하였고 나머지 한 마리의 혈관은 혈관류(aneurysm)가 발생하였다. 그러나 자가 세포를 이식한 실험군 4마리 중 2마리는 각각 4주와 6주까지 혈관의 개통성을 유지하였고, 나머지 2마리는 8주까지 혈관의 개통성을 유지하였다. 조직학적 검사 결과, 8주까지 개통성을 유지하였던 혈관은 정상의 혈관과 거의 유사한 조직학적 구조를 나타내었다. 자가 세포와 탈세포화된 지지체를 이용하여 제작한 인공혈관은 조직학적 검사 결과 정상과 유사한 구조로 재생이 가능함을 보여주었다.

• 폴리머
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• 제28권5호
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• pp.382-390
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• 2004

생체적합성 천연재료 중 하나인 탈미네랄화된 골분 (demineralized bone particle, DBP)은 골형성단백질 (BMP)을 함유하고 있어 골수간엽줄기세포 (BMSCs)의 분화를 유도한다. 본 연구에서는 DBP를 함유한 폴리 락타이드 (PLA)와 락타이드-글리콜라이드 공중합체 (PLGA) 다공성 지지체를 용매 캐스팅/염추출법으로 제조하였고, 수은다공측정계 및 전자주사현미경을 이용하여 특성결정 하였다. BMSCs는 골분화 배지를 이용하여 조골세포로 분화시켜 Wright-Giemsa, Alizarin red, von Kossa 및 ALP 염색으로 확인하였다. DBP가 함유된 지지체와 DBP가 함유되지 않은 지지체에 BMSCs를 파종한 후 면역결핍 누드마우스의 피하에 삽입하여 이들의 골형성 정도를 비교하여 보았다. 제조한 지지체의 다공도는 $90.2\%$ 이상이었고 평균 다공크기도 69.1$\mu$m 이상이었다. BMSCs는 Wright-Giemsa, Alizarin red, von Kossa 및 ALP 염색결과 조골세포로 분화가 가능했으며, 동물실험을 수행한 결과 DBP가 함유된 지지체에서 칼슘침착 영역을 확인할 수 있었지만 DBP가 함유되지 않은 지지체에서는 칼슘침착 영역을 확인하지 못하였다. 결론적으로 DBP를 함유한 지지체에서 DBP와 BMSCs가 골형성에 중요한 요인으로 작용한다고 사료된다.

• Archives of Pharmacal Research
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• 제26권1호
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• pp.76-82
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• 2003

Drug releasing porous poly($\varepsilon$-caprolactone) (PCL)-chitosan matrices were fabricated for bone regenerative therapy. Porous matrices made of biodegradable polymers have been playing a crucial role as bone substitutes and as tissue-engineered scaffolds in bone regenerative therapy. The matrices provided mechanical support for the developing tissue and enhanced tissue formation by releasing active agent in controlled manner. Chitosan was employed to enhance hydrophilicity and biocompatibility of the PCL matrices. PDGF-BB was incorporated into PCL-chitosan matrices to induce enhanced bone regeneration efficacy. PCL-chitosan matrices retained a porous structure with a 100-200 $\mu$m pore diameter that was suitable for cellular migration and osteoid ingrowth. $NaHCO_3$ as a porogen was incorporated 5% ratio to polymer weight to form highly porous scaffolds. PDGF-BB was released from PCL-chitosan matrices maintaining therapeutic concentration for 4 week. High osteoblasts attachment level and proliferation was observed from PCL-chitosan matrices. Scanning electron microscopic examination indicated that cultured osteoblasts showed round form and spread pseudopods after 1 day and showed broad cytoplasmic extension after 14 days. PCL-chitosan matrices promoted bone regeneration and PDGF-BB loaded matrices obtained enhanced bone formation in rat calvarial defect. These results suggested that the PDGF-BB releasing PCL-chitosan porous matrices may be potentially used as tissue engineering scaffolds or bone substitutes with high bone regenerative efficacy.

• 폴리머
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• 제31권1호
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• pp.14-19
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• 2007

탈미네랄화된 골분(demineralized bone particle, DBP)은 골/연골 형성의 강력한 유도인자로 사용된다. 본 연구에서는 용매 캐스팅/염 추출법을 이용해 함량별 DBP와 PLGA가 하이브리드화된 다공성 지지체를 실제 디스크 형태와 유사하게 제조하였다. 제조된 지지체의 특성을 분석하기 위하여 다공도, 표면 젖음성 및 물 흡수성을 측정하였다. 디스크 세포인 섬유륜 및 수핵 세포는 토끼로부터 분리하여 제조된 지지체에 각각 파종한 후, 지지체를 재조합하여 배양하였다. 지지체에 파종된 디스크 세포의 생존율과 증식률은 MTT(3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium-bromide) 분석 방법을 이용하였고, 면역결핍 쥐의 피하에 삽입하여 이들의 디스크 조직 형성 정도를 확인하였다. 피하에 이식된 지지체를 적출하여 육안으로 관찰하고 모폴로지의 변화를 확인한 후, 조직을 파라핀으로 고정시켜 슬라이드를 제조하여 hematoxylin과 eosin 염색을 수행하였다. 천연/합성 하이브리드 담체로서의 DBP/PLGA 담체가 PLGA 단독으로 사용하였을 때와 비교하여 볼 때 디스크 조직의 형성이 우수하였으며, 특히 20, 40%의 DBP가 함유된 지지체가 세포의 성장과, 디스크 조직화에 유리함을 확인하였다.

• Macromolecular Research
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• 제10권3호
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• pp.158-167
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• 2002

In order to endow with new bioactive functionality from small intestine submucosa (SIS) powder as natural source to poly (L-lactide) (PLA) and poly (lactide-co-glycolide) (PLGA) synthetic biodegradable polymer, porous SIS/PLA and SIS/PLGA as natural/synthetic composite scaffolds were prepared by means of the solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. A uniform distribution of good interconnected pores from the surface to core region was observed the pore size of 40~500 ${\mu}{\textrm}{m}$ independent with SIS amount using the solvent casting/salt leaching method. Porosities, specific pore areas as well as pore size distribution also were almost same. After the fabrication of SIS/PLA hybrid scaffolds, the wetting properties was greatly enhanced resulting in more uniform cell seeding and distribution. Five groups as PGA non-woven mesh without glutaraldehyde (GA) treatment, PLA scaffold without or with GA treatment, and SIS/PLA (Code No.3 ; 1 : 12 of salt content, (0.4 : 1 of SIS content, and 144 ${\mu}{\textrm}{m}$ of median pore size) without or with GA treatment were implanted into the back of nude mouse to observe the effect of SIS on the induction of cells proliferation by hematoxylin and eosin, and von Kossa staining for 8 weeks. It was observed that the effect of SIS/PLA scaffolds with GA treatment on bone induction are stronger than PLA scaffolds, that is to say, in the order of PLA/SIS scaffolds with GA treatment > PLA/SIS scaffolds without GA treatment > PGA nonwoven > PLA scaffolds only with GA treatment = PLA scaffolds only without GA treatment for the osteoinduction activity. The possible explanations are (1) many kinds of secreted, circulating, and extracellular matrix-bound growth factors from SIS to significantly affect critical processes of tissue development and differentiation, (2) the exposure of SIS to GA resulted in significantly calcification, and (3) peri-implant fibrosis due to covalent bonding between collagen molecule by crosslinking reaction. In conclusion, it seems that SIS plays an important role for bone induction in SIS/PLA scaffolds for the application of tissue engineering area.

• Journal of Periodontal and Implant Science
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• 제38권sup2호
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• pp.273-298
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• 2008

Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-$CaF_2-P_2O_5$-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with $500{\sim}800{\mu}m$ of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the $2^{nd}$ days and $4^{th}$ week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권4호
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• pp.243-249
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• 2010

Tissue engineered bone (TEB) can replace an autogenous bone graft requiring an secondary operation site as well as avoid complications like inflammation or infection from xenogenic or synthetic bone graft. Adult mesenchymal stem cells (MSC) for TEB are considered to have various ranges of differentiation capacity or multipotency by the donor site and age. This study examined the effect of age on proliferation capacity, differentiation capacity and bone morphogenetic protein-2 (BMP-2) responsiveness of human bone marrow stromal cells (hBMSC) according to the age. In addition, to evaluate the effect on enhancement for osteoblast differentiation, the hBMSC were treated with Trichostatin A (TSA) and 5-Azacitidine (5-AZC) which was HDAC inhibitors and methyltransferase inhibitors respectively affecting chromatin remodeling temporarily and reversibly. The young and old group of hBMSC obtained from the iliac crest from total 9 healthy patients, showed similar proliferation capacity. Cell surface markers such as CD34, CD45, CD90 and CD105 showed uniform expression regardless of age. However, the young group showed more prominent transdifferentiation capacity with adipogenic differentiation. The osteoblast differentiation capacity or BMP responsiveness was low and similar between young and old group. TSA and 5-AZC showed potential for enhancing the BMP effect on osteoblast differentiation by increasing the expression level of osteogenic master gene, such as DLX5, ALP. More study will be needed to determine the positive effect of the reversible function of HDAC inhibitors or methyltransferase inhibitors on enhancing the low osteoblast differentiation capacity of hBMSC.