Sangjun Lee

Sangjun Lee

Speaker : Hong, Kwan Soo (Principal Researcher, Korea Basic Science Institute) 

Date : 2012-01-17

Location : Room 103-01Pharmacy Hall, Dankook University

Abstract : Magnetic resonance imaging (MRI) is a widely used clinical diagnostic tool because it is non-invasive, provides contrast among soft tissues at high spatial resolution. Conventional MRI focuses almost exclusively on visualizing anatomy and has no specificity for any particular cell type. The 'probe' used in conventional MRI is the proton (1H) in mobile water molecules. New classes of exogenous MRI probes or reagents are needed to facilitate cell-specific imaging in living subjects. Elucidating the trafficking pathways of cells (immune and stem cells) in vivo, together with their migratory properties in relation to their differentiation and activation status, is useful for understanding how the immune system interacts with the related diseases. Methods based on tissue sampling to monitor immune responses are inadequate for repeatedly characterizing the responses of the immune system in different organs. A solution to this problem might come from molecular and cellular imaging - a branch of biomedical sciences that combines biotechnology and imaging methods to characterize, in vivo, the molecular and cellular processes involved in normal and pathologic states. The targeted cells are labeled with magnetic nano-particle-based multimodal contrast agents (CAs) in vivo or in vitro, which gives contrast where the labelled cells are. The CA-mediated in vivo molecular/cellular imaging provides new insights into the biology of cell trafficking and migration, in particular, the recruitment of immune cells into immune disease sites, and the longitudinal tracing of the transplanted cells homing to the disease sites.

Speaker : 박희곤 교수

Date : 2012-01-19

Location : Room 108Pharmacy Hall, Dankook University

Speaker : Dong Wook Han, Ph.D. (건국대학교/Max Planck Institute for Molecular Biomedicine)

Date : 2012-03-27

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Recent studies have shown that defined sets of transcription factors can directly reprogram differentiated somatic cells to a different differntiatied cell type without passing through a pluripotent state, but the restricted proliferative and lineage potential of the resulting cells limits the scope of their potential application. Here we show that a combination of transcription factors(Brn4/Pou3f4, Sox2, Klf4, c-Myc, plus E47/Tcf3) induces mouse fibroblasts to directly acquire a neural stem cell identity-which we term as induced neural stem cells(iNSCs). Direct reprogramming of fibroblasts into iNSCs is a gradual process in which the donor transcriptional program is silenced over time. iNSCs exhibit cell morphology, gene expression, epigenetic features, differentiation potential, and self-renewing capacity, as well as in vitro and in vivo functionality similar to those of wild-type NSCs. We conclude that differentiated cells can be reprogrammed directly into specific somatic stem cell types by defined sets of specific transcription factors.

Tuesday, 21 July 2015 10:10

31 - Microfluidic for Tissue Engineering

Speaker : Jeongyun Kim, Ph.D.(Research Professor, Department of Biomedical Engineering, College of Health Science, Korea University)

Date : 2012-06-08

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Microfluidic 은 1980년대에 잉크젯 프린터로 세상에 알려지기 시작하였으며, 90년대들어 Harvard University 화학과 교수인 George Whiteside에 의해 PDMS라는 polymer를 이용하면서 Biology 에 적용되기 시작하였으며, 오늘날에는 전통적인 생물학적 실험방법으로 실현이 불가능했던 부분들을 microfluidic chip에서 실현함으로써 생물학 발전에 많은 기여를 하고 있다.

이에 본 발표에서는 microfluidic이 biology에 어떻게 적용이 되어 왔으며, 향후 어떤 방향으로 전개되어 갈지에 대해 아래와 같이 3가지 부분에 대해 설명하고자 한다.

1. Lab-on-a-Chip구현을 위한 Microfluidic의 물리적 현상 

2. Tissue Engineering을 위한 Microfluidic의 활용 예(발표자의 연구 결과 포함) 

3. 단국대학교에서 진행중인 연구와 관련한 몇가지 실험적 제안 

Speaker : Takuya Matsumoto, Ph.D. (Professor & Chair, Department of Biomaterials, Graduate School of Medicine, Dentistry and  Pharmaceutical Sciences, Okayama University)

Date : 2012-07-31

Location : Room 107Pharmacy Hall, Dankook University

Abstract : In vitro fabricated biological tissue would be an ultimate implantable material for tissue regeneration. It also would be valuable tools for screening multiple drugs at a time. Thanks to the advancement of tissue engineering studies in the last few decades, researchers now develop several technique to manipulate cells for in vitro tissue synthesis. In this talk, I would like to introduce our materials and technique for in vitro cell and tissue manipulation for the future in vitro tissue synthesis.

Thursday, 23 July 2015 10:10

33 - Strategies in Designing Efficient

Speaker : Yoon Shin Park, Ph.D.  (Research Professor, Ewha Womans University Medical School) 

Date : 2012-08-07

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Cell permeable peptides (CPPs) are known for their versatility in carrying macro- or supramolecules through the cell membrane barriers that challenge the conventional drug-delivery approaches. The CPPs are capable of transporting their cargos, often linked by a covalent bond, into almost all cell types. Among such CPPs, we previously reported a new CPP, low molecular weight protamine (LMWP) peptide (VSRRRRRRGGRRRR) developed by enzymatic digestion of protamine (an FDA-approved drug), as a potent yet nontoxic CPP or membrane translocalization carrier. Both in vitro and animal investigations demonstrated that, via covalent or electrostatic conjugation, LMWP was able to transduce its attached protein, gene or carrier cargo into various types of cells. The LMWP offers distinct advantages. First, LMWP is as potent as the virus-derived TAT peptide, the most-studied CPP to date, in mediating cellular translocation of the attached cargos. Secondly, unlike other CPPs, the toxicity profile of LMWP has already been thoroughly established. LMWP was shown to be nonimmunogenic, and its use in dogs did not elicit acute toxic responses. Lastly, while other CPPs must be chemically synthesized, LMWP can be produced in mass quantities direct from native protamine with limited processing time and cost. More recently, it was shown that cell translocation mediated by LMWP does not cause any perturbation or damage to the cell membrane. Therefore, we suggest that LMWP can be used as a tool to aid intracellular delivery of drugs into target cells.

Speaker : Chan Hum Park, M.D(School of Medicine, Hallym University)

Date : 2012-09-14

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Silk fibroin of silkworms has been widely studied as biomaterials. In our institute, we fabricated various types of biomaterials using silk fibroin. Silk patch presented no cytotoxicity in L929 cells and rat tissue. We investigated the degradation behavior of silk patch in vitro and in vivo, and the effects of repairing large tympanic membrane (TM) perforations in rats with a thin silk patch compared with the commonly used paper patch. The results indicated that silk patch is a good biocompatible and has a long degradation time as biomaterials. Also, we showed that silk patch treatment accelerates wound healing and shortens TM perforation closure time. 

 Next, we fabricated silk fibroin (SF) nanofiber mats by electrospinning to develop biodegradable electrospun dermal scaffolds to replace donor human dermis or bovine collagen for 3D skin reconstruction for future clinical use. We prepared SF nanofiber mats that were recrystallized in different ways. These mats were fabricated by electrospinning with ethanol/propanol mixtures of various blend ratios, and their biodegradabilities in vitro and in vivo were evaluated using rats. As a result, we can suggest an established method to modulate the degradability of SF nanofibrous materials based on long-term (12 months) observations. In particular, we elucidated how the SF nanofibers are degraded and incorporated with surrounding tissue by observation of fluorescein isothiocyanate (FITC)–labeled SF nanofiber in vivo. Also we showed that SF nanofiber mats have a good biocompatibity and effect for wound healing. Our findings suggest that SF nanofiber mats could be materials to be utilized as dermal substitute for tissue engineering.

Speaker : Ki Dong Park, Ph.D. (Dept of Molecular Science and Technology, Ajou University)

Date : 2012-10-10

Location : Room 106Pharmacy Hall, Dankook University

Abstract : For the past three decades, extensive research has been performed in the design of new polymers for a variety of medical applications.  Great progress in therapeutics and diagnostics can be attributed to these scientific advances in biomedical polymers.  A variety of bioinert materials or bioactive materials using drugs, cells, and growth factors are widely utilized for the implants, devices and tissue regeneration.  These materials provide an improved biocompatible materials to host, to significantly decrease or increase the host/tissue/blood response to the foreign materials.   In the future, biomaterials will play a different role in modern therapeutics.   New materials will be tailored to interact more on a protein and cellular level to achieve high degree of biocompatibility, biospecificity and bioacitivity.  

In this presentation, various biocompatible materials such as nanogel and macrogels  (as injectable system) will be demonstrated, which can be utilized as therapeutics implants and therapeutic vehicles for biologically active molecules (cell and drug).

Speaker : Seung Jin Lee Ph.D. Dept. of Pharmacy, Ewha Womans University, Seoul, Korea 

Date : 2012-10-17

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Diseases that cause impaired human organs and tissues have increased due to an expanded life span, natural disasters, and other illnesses.  The essential factors in regenerative therapy include cells, scaffolds and delivery technology of bioactive agents.  Stem cells have been in extremely high demands for tissue regeneration; however, they are somewhat limited in functionality over passages, differentiation potential and sufficient sourcing. 

Stem cell engineering through gene delivery may be possible to enhance its functionality and regeneration capacity. Gene delivery has been beset by low transfection efficiency of inserted gene and poor retention at the applied site.  Alternative non-viral gene delivery technology has thus been pursued for promoted transfection efficiency. Further controlled release from biodegradable scaffolds may overcome the limited longevity of transfected genes during the course of regeneration process. 

CPP could be successfully employed as DNA carrier to stem cells in a form of stable pDNA-CPP complex and markedly increased the transfection efficiency over the existing vectors such as polyplexes and lipoplexes. Controlled gene delivery from fibrous 3-D scaffolds loaded with pDNA/CPP nano-complexes significantly enhanced gene-transfection in a prolonged manner to maximize the regeneration potential. Stem cells are truly promising for regenerative therapy; however, their critical issues still remain in unsettled cell source/outcomes, purity assurance and functionality guarantee. Beyond the general mesenchymal stem cells, i.e., BMSC, UCMSC, ASC, significance of resident stem cells was proved for its profound regeneration function, as strongly supported by innovative isolation process. Novel cell delivery technology was requisite to acquire successful regeneration score. Construction of the stem cells with special target-oriented scaffolds provided key for the treatment of intractable diseases.  These approaches may be highly promising to upgrade the status of tissue regenerative therapy.  In addition, the novel stem cell delivery technology will provide breakthrough and unmet needs for the treatment of intractable diseases.

Speaker : Gun-Il Im, Ph.D. (Dept of Orthopaedics, Dongguk University Ilsan Hospital) 

Date : 2012-10-26

Location : Room 106Pharmacy Hall, Dankook University

Abstract : Adult stem cells have drawn attention as an attractive cell source for tissue regeneration. Mesenchymal stem cells (MSCs) in adults are capable of self-regeneration and differentiation into several cell types. While bone marrow provides the most universal source of MSCs, other tissues such as the periosteum, muscle, synovial membrane and adipose tissue also possess MSCs. Of these, adipose tissue offers a unique source of stem cells with considerable advantages for its accessibility and abundance. The adipose stem cells (ASCs) obtained from lipoaspirates have been also proven to possess the multilineage potential.

The focus of musculoskeletal tissue engineering is the regeneration of bone and cartilage. 

To achieve the goal, an effective induction of differentiation poses a key challenge in the use of adult stem cells. While osteogenic differentiation of bone marrow MSCs is easily induced, ASCs have much lower osteogenic potentials than bone marrow MSCs. It can be enhanced with the used of vitamin D or BMPs. Gene transfer of osteogenic growth factors such as BMPs or transcription factors such as Runx-2 and Osterix can markedly enhance the osteogenic potential of ASCs. Recent advancement in nonviral gene transfer by electroporation has achieved a high transfection rate, and shed a light to their possible clinical application. Chondrogenic differentiation of MSCs poses greater challenge than osteogenic differentiation. TGF- has been used to induce chondrogenesis from MSCs, but the markers of hypertrophy increase along with chondrogenic markers in this setting. Inhibitor of hypertrophy such as PTHrP can be used to induce chondrogenesis while suppressing hypertrophy from MSCs. It is even difficult to induce chondrogenesis from ASCs, requiring greater doses or different combination of growth factors. The nonviral gene transfer of SOX trio, the key transcription factors of chondrogenic differentiation, can also enhance the chondrogenesis from MSCs and ASCs. 

In conclusion, great efforts have been devoted to the research to engineer bone or cartilage from adult stem cells and various strategies for tissue engineering from stem cells have been developed. Nevertheless, a lot of unsolved questions and dilemmas remain until we obtain tissues of high quality from stem cells.