흰쥐의 미숙아망막병증 모델에서 별아교세포와 부챗살아교세포의 형태학적 변화에 관한 연구

한후재(Hoo Jae Hann),김영화(Young Hwa Kim),이희래(Hee Lai Lee) 대한해부학회 2002 Anatomy & Cell Biology Vol.35 No.1

목적 : 미숙아망막병증(retinopathy of prematurity)은 산소치료를 받은 미숙아의 망막에 비정상적인 혈관신생이 일어나는 상태를 가리키며, 고도근시 및 시력소실을 유발할 수 있는 질환이다. 이 질환은 망막혈관의 발생시기에 혈관재배열과정의 조절기전 장애로 인해 발병하는 것으로 여겨지나, 망막내 혈관신생에 관여하는 것으로 알려진 부챗살아교세포와 별아교세포의 형태 변화에 관한 연구는 거의 없다. 이에 연구자는 신생흰쥐에서 미숙아망막병증을 유발하고, 망막신경아교세포들의 형태학적 변화를 살펴보고자 하였다. 방법 : 생후 6일째의 신생흰쥐를 네 군으로 나누어 실험을 진행하였다. 생후 2주까지는 고산소/저산소환경 (산소분압 55/15%, 75/15%, 80/10%; 제 II, III, IV군)에 24시간 주기로 교대로 노출시킨 후 정상산소환경으로 옮겨 사육하였으며, 대조군은 정상산소분압(20.9%; 제 I 군) 하에서 지속적으로 사육하였다. 일정한 시기에 동물을 희생시켜 ADPase 반응으로 혈관발달의 정도를 평가하고, 망막내 신경아교세포들의 형태학적 변화를 전자현미경으로 살펴보았다. 결과 : 산소분압차가 가장 크고 저산소증의 정도가 심한 제IV 군에서는 생후 2주 이후에 희생시킨 12예 중 4예에서, 그 리고 제 III 군에서는 2예에서, ADPase 반응상 유리체 내로의 혈관신생이 확인되었다. 유리체 내로 혈관신생이 일어난 경우,부챗살아교세포의 세포질돌기로 이루어진 속경계막의 해체소견과 더불어 부챗살아교세포의 세포질이 이루는 속핵층 신경세포 사이간격의 감소가 관찰되었으나, 세포질 돌기내의 세포소기관들은 비교적 잘 유지되어 있었다. 별아교세포의 변성소견은 관찰되지 않았으며, 망막내 출혈부위나, 유리체-망막경계면에서는 미세아교세포나 포식세포의 침윤이 관찰되었다. 속핵층에서는 신경세포로 여겨지는 일부 세포들의 세포사 소견이 관찰되었다. 결론 : 미숙아망막병증에서 나타나는 비정상적인 혈관신생에는 부챗살아교세포돌기의 퇴축과 이로 인한 속경계막의 균 열이 주요요인으로 작용하는 것으로 보이며, 별아교세포는 형태학적으로 뚜렷한 변화를 보이지 않았다. Objectives : Retinopathy of prematurity (ROP) is one of the major cause of vision loss among children. Recently, the prevalence of ROP is markedly increasing as the survival rate of very-low-birth-weight premature infants has been improved. It is widely accepted that retinal hypoxia results in the release of factors influencing new blood vessel growth. But, it is little known about the morphological changes of retinal astrocytes and Muller cells in the ROP model. So, we planned to investigate the morphological changes of those retinal glial cells induced by alternating hyperoxic and hypoxic injury in ROP. Methods : Newborn rats (postnatal day 6) were exposed to two different oxygen concentrations alternating every 24 hours until postnatal day 14. Used oxygen concentrations were 10~15% for hypoxic episode and 55~80% for hyperoxic episode. Afterthen, they were returned to room air. A group of animal served as a room air control. Retinal vascularity was assessed by ADPase reaction and morphology of retinal glial cells was observed using transmisson electron microscope. Results : Preretinal neovascular tufts were observed in 2 out of 12 animals of group III (75/10%) and 4 out of 12 animals of group IV (80/10%), respectively. There was no remarkable structural change of astrocytes. But we could observe some morphological changes of Muller cells. Retraction of the radial processes of Muller cells and breaking of basal lamina were noted at the site of preretinal neovascularization. Decrease in the space occupied by the cytoplasmic processes of Muller cells was observed in the inner nuclear layer of group IV retinae. Infiltration of microglia or macrophage into the vitreo-retinal interface and the site of extravasation was noted. Findings suggestive of neuronal cell death were also observed especially in the inner nuclear layer. Conclusions : Morphological change of Muller cells and resultant loss of integrity of internal limiting membrane seemed to be the most important step for preretinal neovascularization. But, no structural changes of astrocytes were noted.

Invited Mini Review : Regeneration of the retina: toward stem cell therapy for degenerative retinal diseases

( So Hee Jeon ),( Il Hoan Oh ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.4

Degenerative retinal diseases affect millions of people worldwide, which can lead to the loss of vision. However, therapeutic approaches that can reverse this process are limited. Recent efforts have allowed the possibility of the stem cell-based regeneration of retinal cells and repair of injured retinal tissues. Although the direct differentiation of pluripotent stem cells into terminally differentiated photoreceptor cells comprises one approach, a series of studies revealed the intrinsic regenerative potential of the retina using endogenous retinal stem cells. Muller glial cells, ciliary pigment epithelial cells, and retinal pigment epithelial cells are candidates for such retinal stem cells that can differentiate into multiple types of retinal cells and be integrated into injured or developing retina. In this review, we explore our current understanding of the cellular identity of these candidate retinal stem cells and their therapeutic potential for cell therapy against degenerative retinal diseases. [BMB Reports 2015; 48(4): 193-199]

당뇨 유발 쥐의 망막에서 효소조직화학염색에 의한 뮐러세포의 형태학적 연구

문수정,김인철,이동욱,신화,조남천 대한안과학회 2007 대한안과학회지 Vol.48 No.5

Purpose: To evaluate the morphological changes in Muller cells of an induced diabetic rat model with carbonic anhydrase histochemical staining. Methods: Retinae of three normal rats and four streptozotocin-induced diabetic rats were used. The morphological changes in the Muller cells of these retinae were observed using enzyme histochemical staining. Results: The numbers of positive staining Muller cells in diabetic rats retinae were significantly lower than those of the normal rats. In addition, the shape of the Muller cell bodies in the streptozotocin-induced diabetic rat model’s retina changed from polygonal to abnormally flat. Furthermore, the staining of the Muller cells’ segment in the outer nuclear layer of the diabetic rat’s retinae were weaker, and some Muller cell segments were not stained at all. Conclusions: The numbers of Muller cells in diabetic rats’ retinae were significantly lower than those of the normal rats. In addition, the features of Muller cell bodies of the diabetic rats were changed morphologically.

Regulatory Expression of Vanilloid Receptors 1 in the Rat Retina Following Ischemia-Reperfusion Injury

( Bong Min Kim ),( Heung Jae Chun ),( Myung Hoon Chun ),( Wha Sun Kang ) 한국조직공학·재생의학회 2011 조직공학과 재생의학 Vol.8 No.2

The vanilloid receptor subtype 1 (VR1), also known as transient receptor potential channel vanilloid subfamily member 1, is a nonselective cation channel that is activated by a ligand, protons, or heat. To identify the functional role of the VR1 in response to ischemic injury in the retina, we investigated the spatiotemporal expression of the VR1 in the rat retina after ischemia-reperfusion. The VR1 was induced in Muller cells and ganglion cells in rat retina after ischemia-reperfusion. The expression of the VR1 in Muller cells was downregulated in the early stage of reperfusion and increased with increasing reperfusion time after ischemic injury. VR1 immunoreactivity in ganglion cells also increased with increasing reperfusion time after the early stage of ischemia-reperfusion. Immunoblot analysis confirmed the immunohistochemically determined temporal patterns of the VR1. These results suggest that the VR1 may mediate neurotoxicity or neuroprotection, depending on the duration of reperfusion after ischemic injury.

Effects of Histone Deacetylase Inhibitor (Valproic Acid) on the Expression of Hypoxia-inducible Factor-1 Alpha in Human Retinal Müller Cells

Young Jun Kim,Sang Jun Park,Na Rae Kim,Hee Seung Chin 대한안과학회 2017 Korean Journal of Ophthalmology Vol.31 No.1

Purpose: To evaluate the effects of valproic acid (VPA), a histone deacetylase inhibitor (HDACI), on the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) in human retinal Müller cells under hypoxic conditions. Methods: Chemical hypoxia was induced in human retinal Müller cells (MIO-M1) by treatment with increasing concentrations of cobalt(Ⅱ) chloride (CoCl2). Müller cells were also treated with a set concentration of CoCl2, along with various concentrations of VPA. The expression of HIF-1α and VEGF in the treated Müller cells was determined by enzyme-linked immunosorbent assay. Results: Exposure of human retinal Müller cells to increasing concentrations of CoCl2 produced a dose-dependent increase in HIF-1α expression. The addition of increasing concentrations of VPA lead to a dose-dependent decrease in expression of HIF-1α and VEGF in Müller cells exposed to a set concentration of CoCl2. Conclusions: HDACI VPA downregulated the expressions of HIF-1α and VEGF in human retinal Müller cells under hypoxic conditions. Using HDACI to target HIF-1α expression in Müller cells could be a new therapeutic strategy for the treatment of retinal vascular diseases.

Differential response of Müller cell and microglia in a mouse retinal detachment model and its implications in detached and non-detached regions

Seung Hee Lee,Yong Soo Park,In-Beom Kim 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Retinal detachment (RD) is a sight-threatening condition that leads to photoreceptor cell death, but only few studies provide overall insight throughout the entire retinal region. In this study, we examined the spatiotemporal changes in glial cell responses in a mouse RD model 14 d after RD, focusing on the border and intact regions. In scotopic electroretinography, both a- and b-waves reduced time-dependently. Hematoxylin and eosin staining revealed that the thickness of the outer nuclear layer (ONL) gradually decreased throughout the retinal region. Terminal deoxynucleotidyltransferase dUTP nick end labeling (TUNEL) assay showed that TUNEL-positive photoreceptors were significantly increased 5 d after RD and thereafter, decreased by 14 d. Retinal inflammation was evaluated immunohistochemically using antibodies against a Müller glial response marker, glial fibrillary acidic protein (GFAP), and two microglial cell markers, Iba-1 and osteopontin (OPN). GFAP immunoreactivity increased 7 d after RD in complete RD and was retained for 14 d. OPN expression increased in Iba-1-labeled microglial cells 3–7 d after RD, along with an increase in Iba-1-labeled microglial cells, and thereafter, decreased by 14 d in the detached and border regions. During the entire experimental period, however, OPN was not expressed in the intact region, where morphologically activated Iba-1-labeled microglial cells were observed. These retinal glial cell responses and photoreceptor degeneration sustained by RD for 14 d in border and intact regions suggest that the effects of RD in the border and intact retinal regions are underestimated.