We would like to acknowledge Dr. Bradley Schulte for comments on this protocol. This work was supported by National Institutes of Health grant R00 (5R00DC010220). This project was performed in a renovated laboratory space supported by Grant C06RR014516.

참고 : 살아있는 동물을 사용하는 모든 프로토콜을 검토하고 기관 동물 관리 및 사용위원회 (IACUC)의 승인을 공식적으로 실험 동물의 관리 및 사용 방법을 승인 따라야합니다. 모든 해부은 층류 클린 벤치에 무균 기술을 사용하여 수행되어야한다. 장갑과 마스크를 원하는 경우,이 절차를 수행하는 동안 착용해야합니다. 배아 마우스 내부 귀 1. 해부 <ol><li> 코르티 이식편 문화의 기관에 대한 설정 : <ol><li> 약 30 분 동안 UV 광을 켜서 층류 조직 배양 후드를 소독하고 사용 전에 70 %의 에탄올로 표면을 소독. 또한, 미세 해부 도구와 오토 클레이브를 통해 배아 해부 또는 사용하기 전에 적어도 20 분 동안 70 % 에탄올에 몸을 담글하여 실 가드 코팅 요리를 포함한 모든 해부기구를 소독. 깨끗한 층류 클레아에서 자연 건조 요리와 악기를 70 % 에탄올을 붓고 허용N 벤치 사용 전에. </li><li> 준비 멸균 행크의 균형 잡힌 염 용액 (HBSS) / (4- (2- 히드 록시 에틸) -1- 피페 라진 에탄 술폰산) HEPES 배 HBSS 및 0.5 %의 10 %를 첨가하여 약 7.2로 pH를 조정하고 필터 멸균함으로써 (HEPES) 혼합물 4 ° C에서 최종 솔루션 및 저장. 더 나은 절차 전반에 걸쳐 조직을 유지하기 위해 냉장 HBSS / HEPES 솔루션의 모든 해부를 수행합니다. </li><li> 멸균 15 ml의 폴리 프로필렌 튜브에 기저막 매트릭스의 300 μL 분취 멸균 (39 ° C) 냉간 둘 베코 변형 이글 중간 (DMEM) 5 mL를 추가하여 기저막 매트릭스 코트 유리 바닥 접시. 내용을 텍싱하여 혼합하고 접시의 중앙에 잘 존재하는 전체 문화를 덮도록 각각의 배양 접시의 중앙에 기저막 매트릭스 DMEM 혼합물의 150 μl를 추가합니다. 사용하기 전에 적어도 45 분 동안 37 ° C를 인큐베이터에서 요리와 저장소를 커버. </li><li> 일에 HBSS를 차게 4-5 ml에 붓고살균 폴리스티렌 페트리 접시를 REE 후드 폐쇄 둡니다. </li><li> DMEM 9 ㎖, N2 보충제 100 ㎕, 10g / ㎖ 시프 FBS 및 1 ㎖를 첨가하여 15 ㎖의 멸균 된 폴리 프로필렌 튜브에서 배양 배지를 준비한다. </li></ol></li><li> 배아의 분리 : 참고 : 배아 마우스에서 인공 와우 절편을 배양이 절차에서는 수확 내이가 배아 일 (E)에서 수정 후 하루 13 시간 뼈 E1 (9)으로 간주된다. 프로토콜은 또한 E12 E18로부터 시작하여 마우스 배아 내이 함께 사용될 수있다. <ol><li> CO 2 시간 초과 - 임신 한 마우스를 안락사와 자궁 경부 전위 또는 적절한 승인 프로토콜에 의해 동물을 희생. 조직 배양 무균 룸을 유지하는 거리 층류 유동 조직 배양 후드에서 euthanization을 수행. </li><li> 이 위로 향하게 복부와 종이 타월에 안락사 마우스를 놓고 70 % 에탄올로 복부를 소독. </li><li> 피부를 잡아 복강을 엽니 다다른 손을 사용하여 가위로 중간 선을 따라 곡선 한 손으로 집게와 컷 표피와 근육으로. 양쪽에 두 개의 수직 컷을 확인하고 집게로 양측 자궁 뿔을 들어 올려 조심스럽게 자궁을 끌어와 결합 조직을 이용하여 위 아래에서 분리. </li><li> 층류 흐름 클린 벤치에 냉장 해부 솔루션 (HBSS / HEPES 혼합물) 및 전송을 포함하는 페트리 접시에 배아 체인을 놓습니다. </li><li> 태반에서 조심스럽게 배아를 제거하고 해부 솔루션을 포함하는 멸균 페트리 접시 중 하나에 배치합니다. 이 솔루션은 피 묻은 켜지면 새로운 배양 접시로 이동합니다. 참고 :이 시점에서, 배아 Theiler의 준비 가이드를 사용하여 개최 할 수있다. </li><li> 깨끗한 집게 나 가위로 목 부위에 집어 배아 목을 벨 및 냉장 해부 솔루션을 포함하는 새로운 배양 접시에 머리를 배치합니다. </li></ol></li><li> 내이의 해부 : <ol><li> 장소 오차가운 해부를 포함하는 멸균 실 가드 접시에 북동 배아 머리 </li><li> 솔루션입니다. ~ 1.6 배의 배율로 해부 현미경 작업, 눈 영역 (도 1a)에 또는 주위 가까이 Minutien 핀을 배치하여 배아 헤드를 고정시킨다. </li><li> 멸균 포셉 두 쌍을 사용하여 조심스럽게 피부를 제거하고 중간 선 (그림 1B)를 따라 등쪽에 두개골을 엽니 다. 두개강 및 시간 뼈에 위치한 내이가이 단계 (그림 1C, D)에서 확인할 수 있습니다에서 뇌를 제거합니다. 일반적으로 내측 귓전 존재 혈관의 라이닝은,이 단계 (도 1d)에서 내이를 식별하기위한 랜드 마크로서 사용될 수있다. </li><li> 조직 아래에있는 집게를 배치하고 차가운 해부 솔루션을 포함하는 새 접시에 두개골 및 전송의 기지에서 내이 (內耳)를 분리하여 시간적 뼈 안쪽 귀를 해부하다 (그림 1E, F). </li></ol></li></ol> 코르티 이식편 문화의 장기의 2 세대 주 :이 개발 단계에서 연골 조직되어 쉽게 집게를 사용하여 절개 될 수있다. <ol><li> 동양 복부 측면은 (그림 2A)을 위로 향하게 조심스럽게 내이 (그림 2B)의 전정 부분을 통해 Minutien 핀의 날카로운 끝을 삽입하여 내부 귀를 안정화되도록 내이. </li><li> 사용하여 초 미세 집게는 달팽이관 (그림 2C)에서 연골을 제거 조심스럽게 원창 근처 집게의 한쪽 끝을 사용하여 절개를하여 상부 연골을 오픈. 참고 :이 위에있는 연골이 때때로 아래에 긁어 기본 인공 와우 덕트에서 연골을 해제 폐쇄 집게를 사용하는 것이 도움이되는 경우에 인공 와우 덕트와 융합 될 때 집게가 연골에 너무 깊이 삽입되지 않도록하는 것이 중요하다 에스연골의 urface. 이런 개발 단계에서, 달팽이관 나선 길이 차례 만 사분의 삼이다. </li><li> 다음으로,베이스 또는 매우 정점에 하나, 인공 와우 덕트의 선호 지역에 집게를 배치하여 감각 상피를 노출, 부드럽게 달팽이관 (그림 2D)의 지붕을 잡아 당겨. 참고 : 달팽이관의 지붕은 분석을 방해 감각 상피 마스크 수를 완전히 제거해야합니다. 참고 :이 감각 상피가 찢어 쉽기 때문에이 절차는 조심스럽게 수행해야합니다. </li><li> 인공 와우 이식편의 기초가 균일하게 평면이되도록 마지막 단계로, 신중하게 노출 된 감각 상피에서 기본 결합 조직을 제거합니다. </li><li> 집게를 사용 내이의 전정 부분에서 해부 달팽이관을 분리합니다. 이 단계 전이나 2.4 (도 2E) 후에 수행 될 수있다. </li><li> 지하 membra으로 해부하는 인공 와우 감각 상피로 이동네브라스카 매트릭스 코팅 문화가 아니라 1.5 mm 멸균 치우는 삽 (그림 2 층)를 사용. </li><li> 동양은 상피 세포의 내강 표면에 인공 절편이 위를 향하도록 조심스럽게 조직을 평평하고 부드럽게 접시에 추가하여 신선한 배양액 150 μL로 교체하는 기저막 매트릭스 DMEM 솔루션을 대기음. 케어는 각 절편이 코팅 된 유리 커버 슬립에 잘 부착 및 배양 배지에 떠 있지 않도록주의해야한다. 인공 절편 손상을 방지하기 위해 유리 웰에 부착하는 동안 포셉의 팁까지 지적되어 있는지 확인합니다. </li><li> 부드럽게 시간의 원하는 기간, 체외에서 일반적으로 3-6일 (DIV) 5 % CO 2와 37 ° C에서 조직 문화 인큐베이터에서 멸균 150mm 배양 접시와 장소에 배양 접시를 전송합니다. 1 DIV 후, 인공 절편이 배양 접시에 잘 부착되었는지 확인하기 위해 해부 현미경으로 문화를 검사합니다. </li><li> 의 후시간의 원하는 길이에 대한 시험 관내에서 cubation는, 문화는 면역 조직 화학 염색에 대한 처리됩니다. 참고 : 절편 문화가 일반적으로 개발 단계, P0에 해당 6 DIV 동안 배양한다. 체외에서 배양 후, 문화가 면역 조직 화학 등 다운 스트림 응용 프로그램 (그림 3B)에 대해 처리 할 수있는, RT-PCR, 현장 하이브리드 및 / 또는 웨스턴 블롯에. </li></ol> 3. 일렉트로 매개 유전자 전달 <ol><li> 전기에 대한 설정 : <ol><li> 고압 증기 멸균 또는 약 20 분 동안 70 % 에탄올에 몸을 담글에 의해 하나의 100mm를 실 가드 코팅 유리 접시를 소독하고 사용하기 전에 클린 벤치에서 자연 건조 할 수 있습니다. </li><li> 적절한 붙여서 또는 미디 준비 키트를 사용하여 선택의 발현 벡터에서 DNA를 준비합니다. 이 프로토콜에서 사용 된 발현 벡터 및 pIRES2-Atoh1.EGFP pCLIG-NeuroD1.EGFP이다. DNA의 최종 농도는 균 DNA가 적어도 1 ㎍ / μL되어야 /의 RNA 분해 효소가없는 물을. </li></ol></li><li> 배아 인공 외식에 DNA를 Electroporating : <ol><li> 신선한 100mm의 실 가드 코팅 접시에 플라스미드 DNA 용액 10 μl를 추가하고 DNA 용액에 (단계 2.5에서 얻은) 완벽 해부 인공 절편을 전송합니다. </li><li> 이 접시의면에 수직이다 있도록이 위를 향하도록 상피 세포의 내강 표면으로, 약간 달팽이관을 기울입니다. </li><li> 감각 상피과 달팽이관의 기지에 인접 긍정적 인 패들 (양극)으로 부정적인 패들 (음극)과 달팽이관의 양쪽에 전극 패를 놓습니다. 주 : DNA는 음으로 대전되기 때문에,이 정극과 감각 상피에 인접한 프로브의 캐소드 단부를 배치하여 음극으로부터 마이그레이션; DNA는 주로 감각 상피의 표면을 통해 이동합니다. </li><li> electroporator를 사용하여, 24 MV의 9-10 펄스를 제공, t에 발 페달 스위치를 30 밀리 초 펄스 지속 시간그는 electroporator 다음 일렉트릭 달팽이관에 따뜻한 문화 매체의 100 μl를 추가합니다. </li><li> 반복하여 모든 인공 와우 외식과 관심의 모든 유전자의 DNA에 대한 3.2.1-4 단계 및 (단계 2.7) 도금의 기저막 매트릭스 코팅 접시에 일렉트릭 cochleae을 전송합니다. 다음 면역 세포 화학 처리됩니다 시간의 원하는 길이가 37 ° C, 5 % CO 2 가습 인큐베이터 문화 모든 일렉트릭 cochleae. 참고 : CD1 마우스 (약 8 ~ 12 새끼)의 전체 쓰레기에서 달팽이관은 고립 microdissected, 일렉트로 및 &lt;4 시간에서 도금 될 수있다. </li></ol></li></ol> 4. 분석 달팽이 이식편 문화의 참고 : 문화는 일반적으로 개발 단계, P0에 해당 6 DIV 동안 배양한다. 체외에서 배양 후, 문화는 고정되어 면역 세포 화학 처리. <ol><li> Inc.의 원하는 길이 후ubation, 배지를 제거하고 신속 인산염 완충 식염수 (PBS)에 인공 이식편을 헹구고, 실온에서 15 분 동안 (PBS에서 제조) 4 % 파라 포름 알데히드에서 배양한다. </li><li> 15 분 동안 세 번 추가 PBS에 의해 정착을 씻고 PBS에 헹군다. </li><li> 10 % 염소 혈청을 함유하는 PBS-T로 차단되기 전에 30 분 동안 PBS-T (PBS + 0.5 % 트윈)을 사용 Permeabilize 하시려면. </li><li> 4 ℃에서 하룻밤 1 % 염소 혈청 PBS-T에서 일차 항체를 포함하는 일차 항체 용액에 품어. </li><li> 적절한 알렉사 - 복합 이차 항체를 추가하기 전에 PBS-T 15 분을 각각 사용하여 실온에서 달팽이관을 세 번 씻으십시오. </li><li> 인공 절편 유리 커버 슬립에 배양이기 때문에 그것은 접시에서 커버 슬립을 분리하고 슬라이드에 장착하여 개별적으로 처리 할 수​​ 있습니다. 이것은 실온에서 적어도 1 시간 동안 용매 OS30에서 배양 접시를 담글함으로써 달성 될 수있다. 멸균 면도날을 사용하여 D에서 커버 슬립을 분리흉내과 슬라이드에 탑재하고 형광 현미경으로 시각화. </li></ol>

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W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibitors+of+differentiation+and+DNA+binding+(Ids)+regulate+Math1+and+hair+cell+formation+during+the+development+of+the+organ+of+Corti.">Inhibitors of differentiation and DNA binding (Ids) regulate Math1 and hair cell formation during the development of the organ of Corti.</a> J Neurosci. 26 (2), 550-558 (2006).</li><li>Dabdoub, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sox2+signaling+in+prosensory+domain+specification+and+subsequent+hair+cell+differentiation+in+the+developing+cochlea.">Sox2 signaling in prosensory domain specification and subsequent hair cell differentiation in the developing cochlea.</a> Proc. Natl. Acad. Sci. U.S.A. 105 (47), 18396-18401 (2008).</li><li>Doetzlhofer, A., Basch, M. L., Ohyama, T., Gessler, M., Groves, A. K., Segil, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hey2+regulation+by+FGF+provides+a+Notch-independent+mechanism+of+maintaining+pillar+cell+fate+in+the+organ+of+Corti.">Hey2 regulation by FGF provides a Notch-independent mechanism of maintaining pillar cell fate in the organ of Corti.</a> Dev Cell. 16 (1), 58-69 (2009).</li><li>Puligilla, C., Dabdoub, A., Brenowitz, S. D., Kelley, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sox2+induces+neuronal+formation+in+the+developing+cochlea.">Sox2 induces neuronal formation in the developing cochlea.</a> J Neurosci. 20 (2), 714-722 (2010).</li><li>Kaufman, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Atlas of Mouse Development. , (1995).</li><li>Sher, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+embryonic+and+postnatal+development+of+the+inner+ear+of+the+mouse.">The embryonic and postnatal development of the inner ear of the mouse.</a> Acta Otolaryngol Suppl. 285, 1-77 (1971).</li><li>Torres, M., Giraldez, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+the+vertebrate+inner+ear.">The development of the vertebrate inner ear.</a> Mech Dev. 71 (1-2), 5-21 (1998).</li><li>Brown, S. T., Martin, K., Groves, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+basis+of+inner+ear+induction.">Molecular basis of inner ear induction.</a> Curr Top Dev Biol. 57, 115-119 (2003).</li><li>Puligilla, C., Kelley, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Building+the+world&#8217;s+best+hearing+aid;+regulation+of+cell+fate+in+the+cochlea.">Building the world&#8217;s best hearing aid; regulation of cell fate in the cochlea.</a> Curr Opin Genet Dev. 19 (4), 368-373 (2009).</li><li>Wu, D. K., Kelley, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+of+inner+ear+development.">Molecular mechanisms of inner ear development.</a> Cold Spring Harb Perspect Biol. 4 (8), a008409 (2012).</li><li>Holt, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viral-mediated+gene+transfer+to+study+the+molecular+physiology+of+the+mammalian+inner+ear.">Viral-mediated gene transfer to study the molecular physiology of the mammalian inner ear.</a> Audiol Neurootol. 7 (3), 157-160 (2002).</li><li>Stone, I. M., Lurie, D. I., Kelley, M. W., Poulsen, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adeno-associated+virus-mediated+gene+transfer+to+hair+cells+and+support+cells+of+the+murine+cochlea.">Adeno-associated virus-mediated gene transfer to hair cells and support cells of the murine cochlea.</a> Mol Ther. 11 (6), 843-848 (2005).</li></ol>

No conflicts of interest declared.

를 포함하여 마우스 내이의 멤브레인 미로 내의 모든 세포 감각, nonsensory과 나선 신경절 신경 세포가 모든 E8 10-14 주위에, 외배엽의 후뇌에 인접 otocyst placodally 유래에서 파생됩니다. E11에서 otocyst의 복부 영역은 달팽이관 덕트를 형성하기 위해 확장 및 개발이 계속되고,되어 달팽이관 내의 상피 세포에서뿐만 아니라 otocyst의 다른 영역들의 그룹은이어서 야기 할 것이다 prosensory 패치로 지?...

The mammalian organ of Corti is comprised of a mosaic of specialized cell types, including two types of mechanosensory hair cells as well as at least four types of nonsensory supporting cells making it an ideal model system to study normal cellular processes like proliferation, fate specification, differentiation and patterning. In addition, the normal development of these different cell types is essential for normal hearing function. Hence, it is crucial to understand the factors, both molecular and cellular, that regulate their development. However, the small size of the mouse cochlea as well as its inaccessibility poses a particular challenge for gene expression studies. Moreover, most of the cell fate specification and patterning events occur during embryonic time periods and are mostly completed before birth. Therefore, identification and characterization of signaling events during embryonic time periods is essential to gain insight into the molecular basis of cochlear morphogenesis. 
Here, we demonstrate a method to culture intact cochlea in vitro from embryonic mouse inner ears. The rationale behind the use of this technique is that cultured cochleae maintain their molecular and morphological characteristics thereby providing a valuable model for investigating potential candidate genes and exploring the mechanisms involved in cochlear morphogenesis. Although transgenic mice can be used for gene expression studies, an in vitro system is often needed for monitoring specific gene functions. Moreover, cochlear cultures can be established from transgenic mouse embryos so that their in vitro development and response to various soluble factors and antagonists can be studied. Although embryos at day 13 (E13) are used in this protocol, cultures from E12 or E14 to early postnatal inner ears can give similar results. 
We also present a gene transfer technique in cultured embryonic cochlear explants using square wave electroporation. Following the isolation of the cochlear explants, electroporation can be used to express DNA plasmids of gene(s) of interest in individual cells within the cochlear duct. This technique serves as a complementary approach to studies utilizing transgenic mice to gain insight into the molecular pathways underlying cellular phenotype. Using this method of gene transfer, a variety of epithelial cell types within the embryonic cochlea are transfected, thereby enabling loss-and gain-of-function analyses at the single-cell level. In addition, electrophysiological studies can also be performed in cochlear explant cultures8. This method of in vitro electroporation is relatively simple and straightforward, combined with minimal damage to the tissue, has resulted in a rapid expansion of this technique.

<table><tbody><tr><td>HBSS</td><td>Gibco</td><td>14065-056</td><td></td></tr><tr><td>HEPES</td><td>Gibco</td><td>15630-080</td><td></td></tr><tr><td>Dulbecco&amp;rsquo;s Modified Medium</td><td>Gibco</td><td>12430-054</td><td></td></tr><tr><td>Fetal bovine serum</td><td>Gibco</td><td>10082</td><td></td></tr><tr><td>N-2 Supplement (100x)</td><td>Gibco</td><td>17502-048</td><td></td></tr><tr><td>Ciprofloxacin hydrochloride</td><td>Cellgro</td><td>61-277-RF</td><td></td></tr><tr><td>Glass Dish 60 mm</td><td>Kimble Chase</td><td>23062-6015/23064-6015</td><td></td></tr><tr><td>Glass Dish 100 mm</td><td>Kimble Chase</td><td>23064-10015/23062-10015</td><td></td></tr><tr><td>Minutien pins</td><td>Fine Science Tools</td><td>26002-15</td><td></td></tr><tr><td>Dumont #5 forceps</td><td>Fine Science Tools</td><td>11251-10</td><td></td></tr><tr><td>Pulse generator</td><td>Protech International Inc</td><td>CUY21Vivo-SQ</td><td></td></tr><tr><td>Glass bottom culture dishes</td><td>MatTek</td><td>P35G-0-10-C</td><td></td></tr><tr><td>Matrigel matrix</td><td>BD Biosciences</td><td>356237</td><td></td></tr><tr><td>Culture dish, 60 x 15 mm</td><td>Becton Dickinson</td><td>353037</td><td></td></tr><tr><td>Tissue culture dishes</td><td>Greiner Bio-one</td><td>639160</td><td></td></tr><tr><td>Phosphate buffered saline</td><td>Gibco</td><td>10010-023</td><td></td></tr><tr><td>OS-30</td><td>Dow Corning</td><td>4021768</td><td></td></tr><tr><td>Fluoromount</td><td>Southern Biotech</td><td>0100-01</td><td></td></tr><tr><td>Conical tubes, 15 ml</td><td>Greiner Bio-one</td><td>188261</td><td></td></tr><tr><td>Myosin 6</td><td>Proteus Biosciences Inc</td><td>25-6791</td><td></td></tr><tr><td>Myosin 7a</td><td>Proteus Biosciences Inc</td><td>25-6790</td><td></td></tr><tr><td>TuJ1</td><td>Sigma</td><td>T2200</td><td></td></tr></tbody></table>

culture of embryonic mouse cochlear explants and gene transfer by electroporation

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair cells are aligned in one row of inner hair cells and three rows of outer hair cells that extend along the basal to apical axis of the cochlea. The explant culture technique described here provides an efficient method to isolate and maintain cochlear explants from the embryonic mouse inner ear. Also, the morphology and molecular characteristics of sensory hair cells and nonsensory supporting cells within the cochlear explant cultures resemble those observed in vivo and can be studied within its intrinsic cellular environment. The cochlear explants can serve as important experimental tools for the identification and characterization of molecular and genetic pathways that are involved in cellular specification and patterning. Although transgenic mouse models provide an effective approach for gene expression studies, a considerable number of mouse mutants die during embryonic development thereby hindering the analysis and interpretation of developmental phenotypes. The organ of Corti from mutant mice that die before birth can be cultured so that their in vitro development and responses to different factors can be analyzed. Additionally, we describe a technique for electroporating embryonic cochlear explants ex vivo which can be used to downregulate or overexpress specific gene(s) and analyze their potential endogenous function and test whether specific gene product is necessary or sufficient in a given context to influence mammalian cochlear development1-8.

We describe a method to isolate cochlea from embryonic inner ears and micro-dissect to expose the sensory epithelium. Once dissected, it may be plated and cultured as an intact cochlear duct (Figure 3) and analyzed by immunohistochemistry. The cultured cochlear explants provide a useful assay to examine the effect of variety of soluble factors and pharmacological drugs on cochlear development. Following dissection of cochlear explants, electroporation technique can be used to misexpress genes of interest...

Watch this Scientific Journal Video about Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation at JoVE.com

Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation

We present a method that describes isolation and culture of cochlear explants from embryonic mouse inner ear. We also demonstrate a method for gene transfer into cochlear explants via square-wave electroporation. The in vitro explant culture coupled with gene transfer technique enables researchers to study the effects of altering gene expression during development.

Electroporation에 의한 배아 마우스 달팽이의 Explants의 문화 유전자 전송

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair ...

culture-embryonic-mouse-cochlear-explants-gene-transfer

Research

JoVE Journal

Developmental Biology

12.8K 조회수.  Medical University of South Carolina, College of Medicine. We present a method that describes isolation and culture of cochlear explants from embryonic mouse inner ear. We also demonstrate a method for gene transfer into cochlear explants via square-wave electroporation. The in vitro explant culture coupled with gene transfer technique enables researchers to study the effects of altering gene expression during development. 

비디오: Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation

Methods for Precisely Localized Transfer of Cells or DNA into Early Postimplantation Mouse Embryos

Manipulation and culture of early mouse embryos is a powerful yet largely under-utilized technology enhancing the value of this model system. Conversely, cell culture has been widely used in developmental biology studies. However, it is important to determine whether in vitro cultured cells truly represent in vivo cell types. Grafting cells into embryos, followed by an assessment of their contribution during development is a useful method to determine the potential of in vitro cultured cells. In this study, we describe a method for grafting cells into a defined site of early postimplantation mouse embryos, followed by ex vivo culture. We also introduce an optimized electroporation method that uses glass capillaries of known diameter, allowing precise localization and adjustment of the number of cells receiving exogenous DNA with both high transfection efficiency and low cell death. These techniques, which do not require any specialized equipment, render experimental manipulations of the gastrulation and early organogenesis-stage mouse embryo possible, allowing analysis of commitment in cultured cell subpopulations and the effect of genetic manipulations in situ on cell differentiation.

We demonstrate a method for grafting cultured cells into defined sites of early mouse embryos to determine their in vivo potential. We also introduce an optimized electroporation method that uses glass capillaries of known diameter, allowing the precise delivery of exogenous DNA into a few cells in the embryos.

초기 Postimplantation 마우스 배아로 세포 나 DNA를 정확하게 현지화 전송하는 방법

Manipulation and culture of early mouse embryos is a powerful yet largely under-utilized technology enhancing the value of this model system. Conversely, ...

연구

발생학

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2&#180;-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr&#160;after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

The auditory organ mediates hearing. Here we present a modified in ovo micro-electroporation method optimized for studying auditory progenitor cell proliferation and differentiation in the developing chicken auditory organ.

치킨 청각 기관에 유전자 전달에 의한<em&gt; 비켜에서</em&gt; 마이크로 전기

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. ...

Canalostomy As a Surgical Approach to Local Drug Delivery into the Inner Ears of Adult and Neonatal Mice

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) has been shown to be a useful approach to local drug delivery into the inner ear. The goal of this article is to describe, in detail, the surgical techniques involved in canalostomy in both adult and neonatal mice. As indicated by fast-green dye and adeno-associated virus serotype 8 with the green fluorescent protein gene, the canalostomy facilitated broad distribution of injected reagents in the cochlea and vestibular end-organs with minimal damage to hearing and vestibular function. The surgery was successfully implemented in both adult and neonatal mice; indeed, multiple surgeries could be performed if required. In conclusion, canalostomy is an effective and safe approach to drug delivery into the inner ears of adult and neonatal mice and may be used to treat human inner ear diseases in the future.

Here we describe canalostomy procedure which allows local drug delivery into the inner ears of adult and neonatal mice through the semicircular canal with minimum damage to hearing and vestibular function. This method can be used to inoculate viral vectors, pharmaceuticals, and small molecules into the mouse inner ear.

성인 및 신생아 쥐의 내 귀에 로컬 약물 전달에 대 한 외과 접근으로 Canalostomy

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) ...

유전학

In vivo Electroporation of Developing Mouse Retina

The functional characterization of genes expressed during mammalian retinal development remains a significant challenge. Gene targeting to generate constitutive or conditional loss of function knockouts remains cost and labor intensive, as well as time consuming. Adding to these challenges, retina expressed genes may have essential roles outside the retina leading to unintended confounds when using a knockout approach. Furthermore, the ability to ectopically express a gene in a gain of function experiment can be extremely valuable when attempting to identify a role in cell fate specification and/or terminal differentiation.
We present a method for the rapid and efficient incorporation of DNA plasmids into the neonatal mouse retina by electroporation. The application of short electrical impulses above a certain field strength results in a transient increase in plasma membrane permeability, facilitating the transfer of material across the membrane 1,2,3,4. Groundbreaking work demonstrated that electroporation could be utilized as a method of gene transfer into mammalian cells by inducing the formation of hydrophilic plasma membrane pores allowing the passage of highly charged DNA through the lipid bilayer 5. Continuous technical development has resulted in the viability of electroporation as a method for in vivo gene transfer in multiple mouse tissues including the retina, the method for which is described herein 6, 7, 8, 9, 10. 
DNA solution is injected into the subretinal space so that DNA is placed between the retinal pigmented epithelium and retina of the neonatal (P0) mouse and electrical pulses are applied using a tweezer electrode. The lateral placement of the eyes in the mouse allows for the easy orientation of the tweezer electrode to the necessary negative pole-DNA-retina-positive pole alignment. Extensive incorporation and expression of transferred genes can be identified by postnatal day 2 (P2). Due to the lack of significant lateral migration of cells in the retina, electroporated and non-electroporated regions are generated. Non-electroporated regions may serve as internal histological controls where appropriate. 
Retinal electroporation can be used to express a gene under a ubiquitous promoter, such as CAG, or to disrupt gene function using shRNA constructs or Cre-recombinase. More targeted expression can be achieved by designing constructs with cell specific gene promoters. Visualization of electroporated cells is achieved using bicistronic constructs expressing GFP or by co-electroporating a GFP expression construct. Furthermore, multiple constructs may be electroporated for the study of combinatorial gene effects or simultaneous gain and loss of function of different genes. Retinal electroporation may also be utilized for the analysis of genomic cis-regulatory elements by generating appropriate expression constructs and deletion mutants. Such experiments can be used to identify cis-regulatory regions sufficient or required for cell specific gene expression 11. Potential experiments are limited only by construct availability.

In vivo Electroporation of Developing Mouse Retina

A method for the incorporation of plasmid DNA into murine retinal cells for the purpose of performing either gain- or loss of function studies in vivo is presented. This method capitalizes on the transient increase in permeability of cell plasma membranes induced by the application of an external electrical field.

개발 마우스 망막의 생체내 Electroporation에

The functional characterization of genes expressed during mammalian retinal development remains a significant challenge.  Gene targeting to generate ...

신경과학

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and the organ of Corti in the coiled cochlea. The cristae and maculae contain vestibular hair cells that transduce mechanical stimuli to subserve the special sense of balance, while auditory hair cells in the organ of Corti are the primary transducers for hearing 1. Cell fate specification in these sensory epithelia and morphogenesis of the semicircular canals and cochlea take place during the second week of gestation in the mouse and are largely completed before birth 2,3. Developmental studies of the mouse inner ear are routinely conducted by harvesting transgenic embryos at different embryonic or postnatal stages to gain insight into the molecular basis of cellular and/or morphological phenotypes 4,5. We hypothesize that gene transfer to the developing mouse inner ear in utero in the context of gain- and loss-of-function studies represents a complimentary approach to traditional mouse transgenesis for the interrogation of the genetic mechanisms underlying mammalian inner ear development6.
The experimental paradigm to conduct gene misexpression studies in the developing mouse inner ear demonstrated here resolves into three general steps: 1) ventral laparotomy; 2) transuterine microinjection; and 3) in vivo electroporation. Ventral laparotomy is a mouse survival surgical technique that permits externalization of the uterus to gain experimental access to the implanted embryos7. Transuterine microinjection is the use of beveled, glass capillary micropipettes to introduce expression plasmid into the lumen of the otic vesicle or otocyst. In vivo electroporation is the application of square wave, direct current pulses to drive expression plasmid into progenitor cells8-10. 
We previously described this electroporation-based gene transfer technique and included detailed notes on each step of the protocol11. Mouse experimental embryological techniques can be difficult to learn from prose and still images alone. In the present work, we demonstrate the 3 steps in the gene transfer procedure. Most critically, we deploy digital video microscopy to show precisely how to: 1) identify embryo orientation in utero; 2) reorient embryos for targeting injections to the otocyst; 3) microinject DNA mixed with tracer dye solution into the otocyst at embryonic days 11.5 and 12.5; 4) electroporate the injected otocyst; and 5) label electroporated embryos for postnatal selection at birth. We provide representative examples of successfully transfected inner ears; a pictorial guide to the most common causes of otocyst mistargeting; discuss how to avoid common methodological errors; and present guidelines for writing an in utero gene transfer animal care protocol.

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mouse inner ear is a placode-derived sensory organ whose developmental program is elaborated during gestation. We define an in utero gene transfer technique consisting of three steps: mouse ventral laparotomy, transuterine microinjection, and in vivo electroporation. We use digital video microscopy to demonstrate the critical experimental embryological techniques.

에 의해 개발 마우스 내이 (内耳)에 진 전송<em&gt; VIVO에서</em&gt; Electroporation

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and ...

Primary Culture and Plasmid Electroporation of the Murine Organ of Corti. 

In all mammals, the sensory epithelium for audition is located along the spiraling organ of Corti that resides within the conch shaped cochlea of the inner ear (fig 1). Hair cells in the developing cochlea, which are the mechanosensory cells of the auditory system, are aligned in one row of inner hair cells and three (in the base and mid-turns) to four (in the apical turn) rows of outer hair cells that span the length of the organ of Corti. Hair cells transduce sound-induced mechanical vibrations of the basilar membrane into neural impulses that the brain can interpret. Most cases of sensorineural hearing loss are caused by death or dysfunction of cochlear hair cells.
An increasingly essential tool in auditory research is the isolation and in vitro culture of the organ explant 1,2,9. Once isolated, the explants may be utilized in several ways to provide information regarding normative, anomalous, or therapeutic physiology. Gene expression, stereocilia motility, cell and molecular biology, as well as biological approaches for hair cell regeneration are examples of experimental applications of organ of Corti explants.
This protocol describes a method for the isolation and culture of the organ of Corti from neonatal mice. The accompanying video includes stepwise directions for the isolation of the temporal bone from mouse pups, and subsequent isolation of the cochlea, spiral ligament, and organ of Corti. Once isolated, the sensory epithelium can be plated and cultured in vitro in its entirety, or as a further dissected micro-isolate that lacks the spiral limbus and spiral ganglion neurons. Using this method, primary explants can be maintained for 7-10 days. As an example of the utility of this procedure, organ of Corti explants will be electroporated with an exogenous DsRed reporter gene. This method provides an improvement over other published methods because it provides reproducible, unambiguous, and stepwise directions for the isolation, microdissection, and primary culture of the organ of Corti.

Primary Culture and Plasmid Electroporation of the Murine Organ of Corti.

This procedure describes a method for the isolation and culture of the murine organ of Corti with or without the spiral limbus and spiral ganglion neurons. We also demonstrate a method for the expression of an exogenous reporter gene in the organ of Corti explant by electroporation.

차 문화와 Corti의 Murine 오르간의 플라스미드 Electroporation.

In all mammals, the sensory epithelium for audition is located along the spiraling organ of Corti that resides within the conch shaped cochlea of the ...

생물학

Long-term Time Lapse Imaging of Mouse Cochlear Explants

Here we present a method for long-term time-lapse imaging of live embryonic mouse cochlear explants. The developmental program responsible for building the highly ordered, complex structure of the mammalian cochlea proceeds for around ten days. In order to study changes in gene expression over this period and their response to pharmaceutical or genetic manipulation, long-term imaging is necessary. Previously, live imaging has typically been limited by the viability of explanted tissue in a humidified chamber atop a standard microscope. Difficulty in maintaining optimal conditions for culture growth with regard to humidity and temperature has placed limits on the length of imaging experiments. A microscope integrated into a modified tissue culture incubator provides an excellent environment for long term-live imaging. In this method we demonstrate how to establish embryonic mouse cochlear explants and how to use an incubator microscope to conduct time lapse imaging using both bright field and fluorescent microscopy to examine the behavior of a typical embryonic day (E) 13 cochlear explant and Sox2, a marker of the prosensory cells of the cochlea, over 5 days.

Live imaging of the embryonic mammalian cochlea is challenging because the developmental processes at hand operate on a temporal gradient over ten days. Here we present a method for culturing and then imaging embryonic cochlear explant tissue taken from a fluorescent reporter mouse over five days.

마우스 인공 와우의 Explants의 장기 시간 경과 영상

Here we present a method for long-term time-lapse imaging of live embryonic mouse cochlear explants. The developmental program responsible for building ...

Ex Utero Culture of Mouse Embryos from Pregastrulation to Advanced Organogenesis

Postimplantation mammalian embryo culture methods have been generally inefficient and limited to brief periods after dissection out of the uterus. Platforms have been recently developed for highly robust and prolonged ex utero culture of mouse embryos from egg-cylinder stages until advanced organogenesis. These platforms enable appropriate and faithful development of pregastrulating embryos (E5.5) until the hind limb formation stage (E11). Late gastrulating embryos (E7.5) are grown in rotating bottles in these settings, while extended culture from pregastrulation stages (E5.5 or E6.5) requires a combination of static and rotating bottle cultures. In addition, sensitive regulation of O2 and CO2 concentration, gas pressure, glucose levels, and the use of a specific ex utero culture medium are critical for proper embryo development. Here, a detailed step-by-step protocol for extended ex utero mouse embryo culture is provided. The ability to grow normal mouse embryos ex utero from gastrulation to organogenesis represents a valuable tool for characterizing the effect of different experimental perturbations during embryonic development.

Ex Utero Culture of Mouse Embryos from Pregastrulation to Advanced Organogenesis

An enhanced platform for whole-embryo culture allows continuous and robust ex utero development of postimplantation mouse embryos for up to six days, from pregastrulation stages until advanced organogenesis. In this protocol, we detail the standard procedure for successful embryo culture using static plates and rotating bottle systems.

엑스 우테로 사전 배후에서 고급 유기발생에 이르는 마우스 배아의 배양

Postimplantation mammalian embryo culture methods have been generally inefficient and limited to brief periods after dissection out of the uterus. ...

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

The inner ear perceives sound and maintains balance using the cochlea and vestibule. It does this by using a dedicated mechanosensory cell type known as the hair cell. Basic research in the inner ear has led to a deep understanding of how the hair cell functions, and how dysregulation can lead to hearing loss and vertigo. For this research, the mouse has been the pre-eminent model system. However, mice, like all mammals, have lost the ability to replace hair cells. Thus, when trying to understand cellular therapies for restoring inner ear function, complementary studies in other vertebrate species could provide further insights. The auditory epithelium of birds, the basilar papilla (BP), is a sheet of epithelium composed of mechanosensory hair cells (HCs) intercalated by supporting cells (SCs). Although the anatomical architecture of the basilar papilla and the mammalian cochlea differ, the molecular mechanisms of inner ear development and hearing are similar. This makes the basilar papilla a useful system for not only comparative studies but also to understand regeneration. Here, we describe dissection and manipulation techniques for the chicken inner ear. The technique shows genetic and small molecule inhibition methods, which offer a potent tool for studying the molecular mechanisms of inner ear development. In this paper, we discuss in ovo electroporation techniques to genetically perturb the basilar papilla using CRIPSR-Cas9 deletions, followed by dissection of the basilar papilla. We also demonstrate the BP organ culture and optimal use of culture matrices, to observe the development of the epithelium and the hair cells.

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

The chick is a cost-effective, accessible, and widely available model organism for a variety of studies. Here, a series of protocols is detailed to understand the molecular mechanisms underlying avian inner ear development and regeneration.

조류 내이 발달을 연구하는 Ovo 및 Ex Ovo 방법에서

The inner ear perceives sound and maintains balance using the cochlea and vestibule. It does this by using a dedicated mechanosensory cell type known as ...

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

The goal of this protocol is to demonstrate the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The technique can be utilized as an in vitro screening tool in hearing research.

신생아 쥐의 달팽이관 Explant 기법으로<em&gt; 체외에서</em&gt; 청력 연구의 스크리닝 도구

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a ...

Electroporation에 의한 배아 마우스 달팽이의 Explants의 문화 유전자 전송

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