• Macromolecular Research
• /
• 제13권1호
• /
• pp.73-79
• /
• 2005

Poly(L-lactic acid-co-succinic acid-co-l,4-butane diol) (PLASB) was synthesized by direct condensation copolymerization of L-lactic acid (LA), succinic acid (SA), and 1,4-butanediol (BD) in the bulk using titanium(IV) butoxide as a catalyst. The weight-average molecular weight ofPLASB was $2.1{\times}10^{5}$ when the contents of SA and BD were each 0.5 mol/100 mol of LA. Electrospinning was used to fabricate porous membranes from this newly synthesized bioabsorbable PLASB dissolved in mixed solvents of methylene chloride and dimethylformamide. Scanning electron microscopy (SEM) images indicated that the fiber diameters and nanostructured morphologies of the electrospun membranes depended on the processing parameters, such as the solvent ratioand the polymer concentration. By adjusting both the solvent mixture ratio and the polymer concentration, we could fabricate uniform nanofiber non-woven membranes. Cell proliferation on the electrospun porous PLASB membranes was evaluated using mouse fibroblast cells; we compare these results with those of the cell responses on bulk PLASB films.

• Macromolecular Research
• /
• 제16권4호
• /
• pp.345-352
• /
• 2008

Poly(lactic-co-glycolic acid) (PLGA) tubes (5 mm in diameter) were fabricated using an electro spinning method and used as a scaffold for artificial blood vessels through the hybridization of smooth muscle cells (SMCs) and endothelial cells (ECs) differentiated from canine bone marrow under previously reported conditions. The potential clinical applications of these artificial blood vessels were investigated using a canine model. From the results, the tubular-type PLGA scaffolds for artificial blood vessels showed good mechanical strength, and the dual-layered blood vessels showed acceptable hybridization behavior with ECs and SMCs. The artificial blood vessels were implanted and substituted for an artery in an adult dog over a 3-week period. The hybridized blood vessels showed neointimal formation with good patency. However, the control vessel (unhybridized vessel) was occluded during the early stages of implantation. These results suggest a shortcut for the development of small diameter, tubular-type, nanofiber blood vessels using a biodegradable material (PLGA).

• Archives of Plastic Surgery
• /
• 제33권5호
• /
• pp.612-615
• /
• 2006

Purpose: An ideal bony construct can be divided into two broad categories: (1) the design and fabrication of biodegradable, biomimetic scaffolds that provide correct signals to induce osteogenesis: (2) the identification of an ideal source of osteoprogenitor cells to seed onto the scaffold. We selected poly-glycolic acid as a synthetic scaffold among various scaffolds because of these properties. Meanwhile, culture medium is supplemented with fetal bovine serum(FBS): such serum contains essential elements such as proteins, hormones, growth factors and trace minerals. The composition of FBS can be ideal for various cell growth in vitro. We supposed that we could enhance bone growth at a fractured site if FBS was mixed with synthetic scaffold-PGA. Methods: We cultured human osteoblasts in five different prepared culture dishes made with FBS and PGA mixture. The mixtures contained different ratio of FBS, that is, 0, 1.5, 3, 7, and 10%. We cultured human osteoblasts for seven days and examined the growth and attachment of the cells at the 1st, 3rd, 5th, 7th days, respectively. Results: In the mixture of 0% FBS and PGA, the growth of the cells lasted for one day. In 1.5 and 3% FBS and PGA, the growth of the cells was examined at the 3rd day, then minimally declined at the 5th and 7th days. In 7% FBS and PGA, the growth of the cells lasted for 5 days, then declined at the 7th day. In 10% FBS and PGA, the growth of the cells lasted for 5 days, then declined at the 7th day. Staining status of the osteoblasts with alkaline phosphatase showed pale pink color in 0% FBS and PGA groups, but bright pink color in 1.5, 3, 7, 10% FBS and PGA groups, especially in 3%, 7%. Conclusion: In consequence, the growth of human osteoblast was higher in the mixture of FBS and PGA groups than in pure PGA ones. It is assumed that the mixture of FBS and PGA affects the proliferation of human osteoblasts.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제31권6호
• /
• pp.478-484
• /
• 2009

Three-dimensional porous scaffolds play an important role in tissue engineering strategies. They provide a void volume in which vascularization, new tissue formation, and remodeling can occur. Like any grafted materials, the ideal scaffold for bone tissue engineering should be biocompatible without causing an inflammatory response. It should also possess biodegradability, which provides a suitable three-dimensional environment for the cell function together with the capacity for gradual resorption and replacement by host bone tissue. Various scaffolds have already been developed for bone tissue engineering applications, including naturally derived materials, bioceramics, and synthetic polymers. The advantages of biodegradable synthetic polymers include the ability to tailor specific functions. The purpose of this study was to examine the osteogenic activity of periosteal-derived cells in a polydioxanone/pluronic F127 scaffold. Periosteal-derived cells were successfully differentiated into osteoblasts in the polydioxanone/pluronic F127 scaffold. ALP activity showed its peak level at 2 weeks of culture, followed by decreased activity during the culture period. Similar to biochemical data, the level of ALP mRNA in the periosteal-derived cells was also largely elevated at 2 weeks of culture. The level of osteocalcin mRNA was gradually increased during entire culture period. Calcium content was detactable at 1 week and increased in a time-dependent manner up to the entire duration of culture. Our results suggest that polydioxanone/pluronic F127 could be a suitable scaffold of periosteal-derived cells for bone tissue engineering.

• 폴리머
• /
• 제32권6호
• /
• pp.516-522
• /
• 2008

생분해성 고분자인 poly(L-lactide-co-glycolide) (PLGA)를 이용한 조직공학용 다공성 지지체에서의 공극률, 공극의 크기, 공극의 모양 등은 주입된 세포들이 안착하여 증식하는데 있어서 중요한 요건 중 하나이다. 본 연구에서는 섬유를 세포와 다공크기와의 관계를 파악하고자 다공형성물질인 염화나트륨을 다섯 개의 범위로 분류하여 용매캐스팅/염추출법을 이용한 다양한 다공크기를 갖는 다공성 지지체를 제조하였다. (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium-bromide) (MMT) 분석방법을 이용하여 제조된 지지체에 파종된 섬유륜 세포의 생존율과 증식률을 확인하였으며, in vitro 환경에서의 콜라겐 양과 DNA량을 측정하였다. In vitro 환경에의 세포간의 발생하는 여러 상호작용을 확인하기 위하여 면역결핍 쥐의 피하에 섬유륜 세포가 파종된 지지체를 이식하여 sulfated g1ycosaminoglycan(SGAG)의 합성정도와 조직학적인 평가를 수행하였다. 결론적으로 $180{\sim}250{\mu}m$ 다공크기를 갖는 지지체에서 높은 세포 생존율과 체내에서의 원할한 세포외기질의 형성을 보임으로써 여타의 지지체보다 섬유를 조직 재생에 적절할 것으로 사료된다.

• 한국결정성장학회지
• /
• 제31권5호
• /
• pp.203-211
• /
• 2021

옥타칼슘포스페이트(OCP, Ca₈H₂(PO₄)₆·5H₂O)는 골전도성과 생체적합성을 가진 생분해성 인산칼슘계 재료 중 하나이다. 기질세포를 자극하여 조골세포로 분화하는 성질을 가지고 있어 빠른 골형성 및 재흡수되는 장점을 가지고 있다. 그러나 OCP가 체내에 삽입되면 분말 사이의 약한 응집력으로 인해 지지체의 형태를 유지하지 못하고 빠르게 분해된다. 반면, OCP와 유사한 결정구조를 갖는 수산화인회석(HA, Ca₁₀(PO₄)₆(OH)₂)은 골결손이 회복된 이후까지도 분해되지 않고 체내에 남아있다. 이 연구에서는 SBF(simulated body fluid) 용액에 HA 첨가량이 다른 OCP/HA disc을 침적한 후 기간에 따른 Weight loss, pH 변화 및 미세구조 변화의 측면에서 분해거동을 조사하였다. 그 결과 OCP/HA disc는 HA 함량에 관계없이 2주 동안 형태를 유지하였다. 특히, 40HA 시편의 표면이 균일하게 용해되는 양상을 보였고 SBF 용액 침적 후 7일 후부터 disc의 표면에 CDHA(calcium deficient hydroxyapatite)가 형성되었다. 이러한 결과는 40HA 시편이 골결손부의 회복을 위한 지지체로 적합하다는 것을 보여준다.

• 대한기계학회논문집B
• /
• 제37권3호
• /
• pp.249-257
• /
• 2013

쾌속조형기술을 이용한 3차원 형상의 인공지지체가 조직공학 적용을 위해 개발되고 제작되었다. 본 연구에서는 폴리머 적층 시스템을 이용한 스캐폴드 제작에 있어 시린지 노즐 부분에 노즐 가이드를 장착하여 폴리머 적층 폭과 높이 실험을 수행하였다. 이 때 인공지지체 제작을 위한 생체재료로 폴리카프로락톤이 사용되었다. 폴리머 적층 공정 조건으로는 600 kPa의 공압과 $125^{\circ}C$의 온도가 이용되었다. 성공적인 와셔 인공지지체 제작을 통해 폴리머 적층 시스템에 적용된 노즐 가이드의 성능이 검증되었다. 결론적으로, 향상된 폴리머 적층 시스템을 이용함으로써 복잡한 형상의 조직공학용 3 차원 인공지지체를 제작할 수 있을 것으로 기대된다.

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

• Macromolecular Research
• /
• 제14권5호
• /
• pp.552-558
• /
• 2006

Biodegradable nanofibrous poly(L-lactic acid) (PLLA) scaffold was prepared by an electrospinning process for use in tissue regeneration. The nanofiber scaffold was treated with oxygen plasma and then simultaneously in situ grafted with hydrophilic acrylic acid (AA) to obtain PLLA-g-PAA. The fiber diameter, pore size, and porosity of the electrospun nanofibrous PLLA scaffold were estimated as $250\sim750nm,\;\sim30{\mu}m$, and 95%, respectively. The ultimate tensile strength was 1.7 MPa and the percent elongation at break was 120%. Although the physical and mechanical properties of the PLLA-g-PAA scaffold were comparable to those of the PLLA control, a significantly lower contact angle and significantly higher ratio of oxygen to carbon were notable on the PLLA-g-PAA surface. After the fibroblasts were cultured for up to 6 days, cell adhesion and proliferation were much improved on the nanofibrous PLLA-g-PAA scaffold than on either PLLA film or unmodified nanofibrous PLLA scaffold. The present work demonstrated that the applications of plasma treatment and hydrophilic AA grafting were effective to modify the surface of electrospun nanofibrous polymer scaffolds and that the altered surface characteristics significantly improved cell adhesion and proliferation.

• Nutritional Sciences
• /
• 제9권4호
• /
• pp.233-239
• /
• 2006

Porous matrices of bioactive polymers such as polyglycolic acid (PGA) or polylactic acid (PLA) can be used as scaffolds in bone tissue growth during bone repair process. These polymers are highly porous and serve as a template for the growth and organization of new bone tissues. We evaluated the effect of PGA and PLA polymers on osteoblastic MC3T3-E1 cell extracellular mineralization. MC3T3-E1 cells were cultured in a time-dependent manner -1, 15, 25d as appropriate - for the period of bone formation stages in one of the five culture circumstances, such as normal osteogenic differentiation medium, PGA-plated, fetal bovine serum (FBS)-plated, PGA/FBS-coplated, and PLA-plated For the evaluation of bone formation, minerals (Ca, Mg, Mn) and alkaline phosphatase activity, a marker for osteoblast differentiation, were measured Alizarin Red staining was used for the measurement of extracellular matrix Ca deposit During the culture period, PGA-plated one was reabsorbed into the medium more easily and faster than the PLA-plated one. At day 15, at the middle stage of bone formation, cellular Ca and Mg levels showed higher tendency in PGA- or PLA-plated treatments compared to non-plated control and at day 25, at the early late stage of bone formation, all three cellular Ca, Mg or Mn levels showed higher tendency as in order of PGA-related treatments and PLA-plated treatments, compared to control even without significance. Medium Ca, Mg or Mn levels didn't show any consistent tendency. Cellular ALP activity was higher in the PGA- or PLA-plated treatments compare to normal osteogenic medium treatment PGA-plated and PGA/FBS-plated treatments showed better Ca deposits than other treatments by measurement of Alizarin Red staining, although PLA-plated treatment also showed reasonable Ca deposit. The results of the present study suggest that biodegradable material, PGA and also with less extent for PLA, can be used as a biomaterial for better extracellular matrix mineralization in osteoblastic MC3T3-E1 cells.