Amniotic fluid characteristics and its application in stem cell therapy: A review


Amniotic fluid (AF) is a clear yellow fluid that surrounds the fetus during pregnancy. The amniotic sac consists of 2 layers: the amnion and the chorion. Osmotic and hydrostatic forces cause the maternal plasma to pass through the fetal skin and generate the AF. AF allows the fetus to grow inside the uterus, supports it from injuries, retains consistent pressure and temperature, and enables the exchange of body chemicals with the mother. At first, it consists of water and electrolytes but after the 12-14th wk the liquid also contains carbohydrates, proteins, lipids, phospholipids, urea, hormones, and some biochemical products. AF appearance is characterized by the grade of cloudiness and the number of flakes of the vernix. The volume of AF increases with the fetus’s growth. Its appearance depends on the gestational age. In addition to differentiated cells, stem cells are also found within the AF. These cells express embryonic-specific cell markers and bear high self-renewal capacity and telomerase activity. AF stem cells possess the potential to differentiate into osteogenic, cardiac, skeletal muscle, lung, neuronal, kidney, bone, cartilage, ovarian and hepatic cells in vitro. They represent a great promise in regenerative medicine for the reconstruction of bio-artificial tissues and organs in vivo. The purpose of this paper was to briefly review the development and function of AF and the application of its stem cells in cell therapy.

Key words: Amniotic fluid, Stem cells, Differentiation, Regeneration, Tissue engineering.

[1] Geer LA, Pycke BFG, Sherer DM, Abulafia O, Halden RU. Use of amniotic fluid for determining pregnancies at risk of preterm birth and for studying diseases of potential environmental etiology. Environ Res 2015; 136: 470–481.

[2] Lim JJ, Koob TJ. Placental cells and tissues: The transformative rise in advanced wound care. In: Fonseca C. Worldwide wound healing-innovation in natural and conventional methods. London: InTech Open; 2016.

[3] Magann EF, Sandlin AT, Ounpraseuth ST. Amniotic fluid and the clinical relevance of the sonographically estimated amniotic fluid volume: Oligohydramnios. J Ultrasound Med 2011; 30: 1573–1585.

[4] Underwood MA, Gilbert WM, Sherman MP. Amniotic fluid: Not just fetal urine anymore. J Perinatol 2005; 25: 341– 348.

[5] Dubil EA, Magann EF. Amniotic fluid as a vital sign for fetal wellbeing. Australas J Ultrasound Med 2013; 16: 62–70.

[6] Sha X-y, Xiong Z-f, Liu H-s, Di X-d, Ma T-h. Maternalfetal fluid balance and aquaporins: From molecule to physiology. Acta Pharmacol Sin 2011; 32: 716–720.

[7] van Otterlo LC, Wladimiroff JW, Wallenburg HC. Relationship between fetal urine production and amniotic fluid volume in normal pregnancy and pregnancy complicated by diabetes. Br J Obstet Gynaecol 1977; 84: 205–209.

[8] Abramovich DR, Garden A, Jandial L, Page KR. Fetal swallowing and voiding in relation to hydramnios. Obstet Gynecol 1979; 54: 15–20.

[9] Brace RA. Physiology of amniotic fluid volume regulation. Clin Obstet Gynecol 1997; 40: 280–289.

[10] van der Knoop BJ, van Schie PEM, Vermeulen RJ, Pistorius LR, van Weissenbruch MM, de Vries JIP. Effect of (minor or major) maternal trauma on fetal motility: A prospective study. Early Hum Dev 2015; 91: 511–517.

[11] Akinbi HT, Narendran V, Pass AK, Markart P, Hoath SB. Host defense proteins in vernix caseosa and amniotic fluid. Am J Obstet Gynecol 2004; 191: 2090–2096.

[12] Rashid H, Kagami M, Ferdous F, Ma E, Terao T, Hayashi T, et al. Temperature during pregnancy influences the fetal growth and birth size. Trop Med Health 2016; 45: 1.

[13] Dawood MY. Hormones in amniotic fluid. Am J Obstet Gynecol 1977; 128: 576–583.

[14] Oliveira FR, Barros EG, Magalhaes JA. Biochemical profile of amniotic fluid for the assessment of fetal and renal development. Braz J Med Biol Res 2002; 35: 215– 222.

[15] Bauk FA, Moron AF, Novo NF, Juliano Y, Rodrigues EB, Kulay Jr L. [A comparative study of the sodium, potassium, urea, creatinine, and uric acid concentrations in the human amniotic fluid between weeks 15–20 and 38–42]. Rev Assoc Med Bras 1996; 42: 7–10. (in Portuguese)

[16] Ghaderi Sh, Soheili Z-S, Ahmadieh H, Davari M, Sanie Jahromi F, Samie S, et al. Human amniotic fluid promotes retinal pigmented epithelial cells’ trans-differentiation into rod photoreceptors and retinal ganglion cells. Stem Cells Dev 2010; 20: 1615–1625.

[17] Sanie-Jahromi F, Ahmadieh H, Soheili Z-S, Davari M, Ghaderi S, Kanavi MR, et al. Enhanced generation of retinal progenitor cells from human retinal pigment epithelial cells induced by amniotic fluid. BMC Res Notes 2012; 5: 182.

[18] Davari M, Soheili Z-S, Ahmadieh H, Sanie-Jahromi F, Ghaderi Sh, Rezaei Kanavi M, et al. Amniotic fluid promotes the appearance of neural retinal progenitors and neurons in human RPE cell cultures. Mol Vis 2013; 19: 2330–2342.

[19] Verpoest MJ, Seelen JC, Westerman CF. Changes in appearance of amniotic fluid during pregnancy - the macroscore. J Perinat Med 1976; 4: 12–25.

[20] Zaretsky MV, McIntire DD, Reichel TF, Twickler DM. Correlation of measured amnionic fluid volume to sonographic and magnetic resonance predictions. Am J Obstet Gynecol 2004; 191: 2148–2153.

[21] Bromley B, Shipp TD, Benacerraf B. Assessment of the third-trimester fetus using 3-dimensional volumes: A pilot study. J Clin Ultrasound 2007; 35: 231–237.

[22] Brace RA, Wolf EJ. Normal amniotic fluid v olume changes throughout pregnancy. Am J Obstet Gynecol 1989; 161: 382–388.

[23] Petrozella LN, Dashe JS, McIntire DD, Leveno KJ. Clinical significance of borderline amniotic fluid index and oligohydramnios in preterm pregnancy. Obstet Gynecol 2011; 117: 338–342.

[24] de Tejada BM, Boulvain M, Dumps P, Bischof P, Meisser A, Irion O. Can we improve the diagnosis of rupture of membranes? The value of insulin-like growth factor binding protein-1. BJOG 2006; 113: 1096–1099.

[25] Storness-Bliss C, Metcalfe A, Simrose R, Wilson RD, Cooper SL. Correlation of residual amniotic fluid and perinatal outcomes in periviable preterm premature rupture of membranes. J Obstet Gynaecol Can 2012; 34: 154–158.

[26] Brizot ML, Liao AW, Nomura RM, Francisco RPV, Zugaib M. Changes in amniotic fluid index after maternal oral hydration in pregnancies with fetal gastroschisis: Initial observations. Fetal Diagn Ther 2010; 28: 87–91.

[27] Oyelese Y. Placenta, umbilical cord and amniotic fluid: The not-less-important accessories. Clin Obstet Gynecol 2012; 55: 307–323.

[28] Casey BM, McIntire DD, Bloom SL, Lucas MJ, Santos R, Twickler DM, et al. Pregnancy outcomes after antepartum diagnosis of oligohydramnios at or beyond 34 weeks’ gestation. Am J Obstet Gynecol 2000; 182: 909–912.

[29] Leibovitch L, Kuint J, Rosenfeld E, Schushan-Eisen I, Weissmann-Brenner A, Maayan-Metzger A. Short-term outcome among term singleton infants with intrapartum oligohydramnios. Acta Paediatr 2012; 101: 727–730.

[30] Chavda RJ, Saini HB. A prospective clinical study of feto-maternal outcome in pregnancies with abnormal liquor volume. Int J Reprod Contracept Obstet Gynecol 2016; 3: 181–184.

[31] Baron C, Morgan MA, Garite TJ. The impact of amniotic fluid volume assessed intrapartum on perinatal outcome. Am J Obstet Gynecol 1995; 173: 167–174.

[32] Stevenson RE, Hall JG, Everman DB, Solomon BD. Human malformations and related anomalies. 3rd Ed. UK: Oxford University Press; 2015.

[33] Magann EF, Doherty DA, Lutgendorf MA, Magann MI, Chauhan SP, Morrison JC. Peripartum outcomes of high-risk pregnancies complicated by oligo-and polyhydramnios: A prospective longitudinal study. J Obstet Gynaecol Res 2010; 36: 268–277.

[34] Leibovitch L, Schushan-Eisen I, Kuint J, WeissmannBrenner A, Maayan-Metzger A. Short-term outcome for term and near-term singleton infants with intrapartum polyhydramnios. Neonatology 2012; 101: 61–67.

[35] Perović M, Garalejić E, Gojnić M, Arsić B, Pantić I, Bojović DJ, et al. Sensitivity and specificity of ultrasonography as a screening tool for gestational diabetes mellitus. J Matern Fetal Neonatal Med 2012; 25: 1348–1353.

[36] Hamza A, Herr D, Solomayer EF, Meyberg-Solomayer G. Polyhydramnios: Causes, diagnosis and therapy. Geburtshilfe Frauenheilkd 2013; 73: 1241–1246.

[37] Prusa A-R, Hengstschlager M. Amniotic fluid cells and human stem cell research: A new connection. Med Sci Monit 2002; 8: RA253–RA257.

[38] Cananzi M, De Coppi P. CD117(+) amniotic fluid stem cells: State of the art and future perspectives. Organogenesis 2012; 8: 77–88.

[39] Siegel N, Rosner M, Hanneder M, Freilinger A, Hengstschläger M. Human amniotic fluid stem cells: A new perspective. Amino Acids 2008; 35: 291–293.

[40] Streubel B, Martucci-Ivessa G, Fleck T, Bittner R. [In vitro transformation of amniotic cells to muscle cells– background and outlook]. Wien Med Wochenschr 1996; 146: 216–217. (in German)

[41] In’t Anker PS, Scherjon SA, Kleijburg-Van der Keur C, Noort WA, Claas FH, Willemze R, et al. Amniotic fluid as a novel source of mesenchymal stem cells for therapeutic transplantation. Blood 2003; 102: 1548–1549.

[42] Prusa A-R, Marton E, Rosner M, Bernaschek G, Hengstschläger M. Oct-4-expressing cells in human amniotic fluid: A new source for stem cell research? Hum Reprod 2003; 18: 1489–1493.

[43] Karlmark KR, Freilinger A, Marton E, Rosner M, Lubec G, Hengstschläger M. Activation of ectopic Oct-4 and Rex- 1 promoters in human amniotic fluid cells. Int J Mol Med 2005; 16: 987–992.

[44] Ditadi A, de Coppi P, Picone O, Gautreau L, Smati R, Six E, et al. Human and murine amniotic fluid c-Kit+Lin- cells display hematopoietic activity. Blood 2009; 113: 3953– 3960.

[45] Crane JF, Trainor PA. Neural crest stem and progenitor cells. Annu Rev Cell Dev Biol 2006; 22: 267–286.

[46] Roobrouck VD, Ulloa-Montoya F, Verfaillie CM. Selfrenewal and differentiation capacity of young and aged stem cells. Exp Cell Res 2008; 314: 1937–1944.

[47] Sessarego N, Parodi A, Podestà M, Benvenuto F, Mogni M, Raviolo V, et al. Multipotent mesenchymal stromal cells from amniotic fluid: Solid perspectives for clinical application. Haematologica 2008; 93: 339–346.

[48] Schiavo AA, Franzin C, Albiero M, Piccoli M, Spiro G, Bertin E, et al. Endothelial properties of third-trimester amniotic fluid stem cells cultured in hypoxia. Stem Cell Res Ther 2015; 6: 209.

[49] Chen J, Lu Zh, Cheng D, Peng Sh, Wang H. Isolation and characterization of porcine amniotic fluid-derived multipotent stem cells. PLoS One 2011; 6: e19964.

[50] Moschidou D, Mukherjee S, Blundell MP, Drews K, Jones GN, Abdulrazzak H, et al. Valproic acid confers functional pluripotency to human amniotic fluid stem cells in a transgene-free approach. Mol Ther 2012; 20: 1953–1967.

[51] Hoseini SM, Montazeri F, Moghaddam-Matin M, Bahrami AR, Heidarian Meimandi H, Ghasemi-Esmailabad S, et al. Comparison of chromosomal instability of human amniocytes in primary and long-term cultures in AmnioMAX II and DMEM media: A cross-sectional study. Int J Reprod Biomed 2020; 18: 885–898.

[52] Moschidou D, Mukherjee S, Blundell MP, Jones GN, Atala AJ, Thrasher AJ, et al. Human mid-trimester amniotic fluid stem cells cultured under embryonic stem cell conditions with valproic acid acquire pluripotent characteristics. Stem Cells Dev 2013; 22: 444–458.

[53] Hoseini SM, Sheikhha MH, Kalantar SM, Matin MM, Aflatoonian B, Bahrami AR, et al. A comparative analysis of immunomodulatory genes in two clonal subpopulations of CD90(+) amniocytes isolated from human amniotic fluid. Placenta 2020; 101: 234–241.

[54] Kim J, Lee Y, Kim H, Hwang KJ, Kwon HC, Kim SK, et al. Human amniotic fluid-derived stem cells have characteristics of multipotent stem cells. Cell Prolif 2007; 40: 75–90.

[55] Torricelli F, Brizzi L, Bernabei PA, Gheri G, Di SL, Nutini L, et al. Identification of hematopoietic progenitor cells in human amniotic fluid before the 12th week of gestation. Ital J Anat Embryol 1993; 98: 119–126.

[56] Tsai MS, Lee JL, Chang YJ, Hwang SM. Isolation of human multipotent mesenchymal stem cells from second trimester amniotic fluid using a novel two-stage culture protocol. Hum Reprod 2004; 19: 1450–1456.

[57] McLaughlin D, Tsirimonaki E, Vallianatos G, Sakellaridis N, Chatzistamatiou T, Stavropoulos-Gioka C, et al. Stable expression of a neuronal dopaminergic progenitor phenotype in cell lines derived from human amniotic fluid cells. J Neurosci Res 2006; 83: 1190–1200.

[58] Gosden C, Brock DJ. Combined use of alphafetoprotein and amniotic fluid cell morphology in early prenatal diagnosis of fetal abnormalities. J Med Genet 1978; 15: 262–270.

[59] Loukogeorgakis SP, De Coppi P. Concise review: Amniotic fluid stem cells: The known, the unknown, and potential regenerative medicine applications. Stem Cells 2017; 35: 1663–1673.

[60] Cananzi M, Atala A, De Coppi P. Stem cells derived from amniotic fluid: New potentials in regenerative medicine. Reprod Biomed Online 2009; 18 (Suppl.): 17–27.

[61] Guillot PV, Gotherstrom C, Chan J, Kurata H, Fisk NM. Human first-trimester fetal MSC express pluripotency markers and grow faster and have longer telomeres than adult MSC. Stem Cells 2007; 25: 646–654.

[62] Baghaban Eslaminejad M, Jahangir S. Amniotic fluid stem cells and their application in cell-based tissue regeneration. Int J Fertil Steril 2012; 6: 147–156.

[63] Daar AS, Greenwood HL. A proposed definition of regenerative medicine. J Tissue Eng Regen Med 2007; 1: 179–184.

[64] Hipp J, Atala A. Sources of stem cells for regenerative medicine. Stem Cell Rev 2008; 4: 3–11.

[65] National Research Counsil and Institute of Medicine Committee on the Biological and Biomedical Applications of Stem Cell Research. Stem cells and the future of regenerative medicine. Washington: DC: The National Academies Press; 2002.

[66] Stultz BG, McGinnis K, Thompson EE, Surdo JLL, Bauer SR, Hursh DA. Chromosomal stability of mesenchymal stromal cells during in vitro culture. Cytotherapy 2016; 18: 336–343.

[67] Kajiwara K, Tanemoto T, Wada S, Karibe J, Ihara N, Ikemoto Y, et al. Fetal therapy model of myelomeningocele with three-dimensional skin using amniotic fluid cell-derived induced pluripotent stem cells. Stem Cell Reports 2017; 8: 1701–1713.

[68] Cipriani S, Bonini D, Marchina E, Balgkouranidou I, Caimi L, Zucconi GG, et al. Mesenchymal cells from human amniotic fluid survive and migrate after transplantation into adult rat brain. Cell Biol Int 2007; 31: 845–850.

[69] Kunisaki SM. Amniotic fluid stem cells for the treatment of surgical disorders in the fetus and neonate. Stem Cells Transl Med 2018; 7: 767–773.

[70] Di Baldassarre A, D’Amico MA, Izzicupo P, Gaggi G, Guarnieri S, Mariggiò MA, et al. Cardiomyocytes derived from human cardiopoietic amniotic fluids. Sci Rep 2018; 8: 12028.

[71] Chun SY, Kwon JB, Chae SY, Lee JK, Bae Js, Kim BS, et al. Combined injection of three different lineages of early-differentiating human amniotic fluid-derived cells restores urethral sphincter function in urinary incontinence. BJU Int 2014; 114: 770–783.

[72] Carraro G, Perin L, Sedrakyan S, Giuliani S, Tiozzo C, Lee J, et al. Human amniotic fluid stem cells can integrate and differentiate into epithelial lung lineages. Stem Cells 2008; 26: 2902–2911.

[73] Morigi M, De Coppi P. Cell therapy for kidney injury: Different options and mechanisms-mesenchymal and amniotic fluid stem cells. Nephron Exp Nephrol 2014; 126: 59–63.

[74] Wang MF, Li YB, Gao XJ, Zhang HY, Lin S, Zhu YY. Efficacy and safety of autologous stem cell transplantation for decompensated liver cirrhosis: A retrospective cohort study. World J Stem Cells 2018; 10: 138–145.

[75] Maraldi T, Riccio M, Pisciotta A, Zavatti M, Carnevale G, Beretti F, et al. Human amniotic fluid-derived and dental pulp-derived stem cells seeded into collagen scaffold repair critical-size bone defects promoting vascularization. Stem Cell Res Ther 2013; 4: 53.

[76] Chang LB, Peng SY, Chou CJ, Chen YJ, Shiu JS, Tu PA, et al. Therapeutic potential of amniotic fluid stem cells to treat bilateral ovarian dystrophy in dairy cows in a subtropical region. Reprod Domest Anim 2018; 53: 433– 441.

[77] Gosemann JH, Kuebler JF, Pozzobon M, Neunaber C, Hensel JHK, Ghionzoli M, et al. Activation of regulatory T cells during inflammatory response is not an exclusive property of stem cells. PLoS One 2012; 7: e35512.

[78] Kunisaki SM, Fuchs JR, Kaviani A, Oh JT, LaVan DA, Vacanti JP, et al. Diaphragmatic repair through fetal tissue engineering: A comparison between mesenchymal amniocyte–and myoblast-based constructs. J Pediatr Surg 2006; 41: 34–39.

[79] da Cunha MGMCM, Zia S, Beckmann DV, Carlon MS, Arcolino FO, Albersen M, et al. Vascular endothelial growth factor up-regulation in human amniotic fluid stem cell enhances nephroprotection after ischemiareperfusion injury in the rat. Crit Care Med 2017; 45: e86– e96.

[80] Cananzi M, Atala A, De Coppi P. Stem cells derived from amniotic fluid: New potentials in regenerative medicine. Reprod Biomed Online 2009; 18: 17–27.

[81] Pan HC, Yang DY, Chiu YT, Lai SZ, Wang YC, Chang MH, et al. Enhanced regeneration in injured sciatic nerve by human amniotic mesenchymal stem cell. J Clin Neurosci 2006; 13: 570–575.

[82] Yeh YCh, Wei HJ, Lee WY, Yu CL, Chang Y, Hsu LW, et al. Cellular cardiomyoplasty with human amniotic fluid stem cells: In vitro and in vivo studies. Tissue Eng Part A 2010; 16: 1925–1936.

[83] Yeh YCh, Lee WY, Yu ChL, Hwang ShM, Chung MF, Hsu LW, et al. Cardiac repair with injectable cell sheet fragments of human amniotic fluid stem cells in an immune-suppressed rat model. Biomaterials 2010; 31: 6444–6453.

[84] Ma X, Zhang Sh, Zhou J, Chen B, Shang Y, Gao T, et al. Clone-derived human AF-amniotic fluid stem cells are capable of skeletal myogenic differentiation in vitro and in vivo. J Tissue Eng Regen Med 2012; 6: 598–613.

[85] Bajek A, Olkowska J, Walentowicz-Sadłecka M, Sadłecki P, Grabiec M, Porowińska D, et al. Human adipose derived and amniotic fluid-derived stem cells: A preliminary in vitro study comparing myogenic differentiation capability. Med Sci Monit 2018; 24: 1733–1741.

[86] Chun SY, Cho DH, Chae SY, Choi KH, Lim HJ, Yoon GS, et al. Human amniotic fluid stem cell-derived muscle progenitor cell therapy for stress urinary incontinence. J Korean Med Sci 2012; 27: 1300–1307.

[87] Kim JA, Shon YH, Lim JO, Yoo JJ, Shin HI, Park EK. MYOD mediates skeletal myogenic differentiation of human amniotic fluid stem cells and regeneration of muscle injury. Stem Cell Res Ther 2013; 4: 147.

[88] Perin L, Giuliani S, Jin D, Sedrakyan S, Carraro G, Habibian R, et al. Renal differentiation of amniotic fluid stem cells. Cell Prolif 2007; 40: 936–948.

[89] Noronha IL, Cavaglieri RC, Janz FL, Duarte SA, Lopes MA, Zugaib M, et al. The potential use of stem cells derived from human amniotic fluid in renal diseases. Kidney Int Suppl (2011) 2011; 1: 77–82.

[90] Marongiu F, Gramignoli R, Dorko K, Miki T, Ranade AR, Serra MP, et al. Hepatic differentiation of amniotic epithelial cells. Hepatology 2011; 53: 1719–1729.

[91] Zheng YB, Zhang XH, Huang ZhL, Lin ChSh, Lai J, Gu YR, et al. Amniotic-fluid-derived mesenchymal stem cells overexpressing interleukin-1 receptor antagonist improve fulminant hepatic failure. PLoS One 2012; 7: e41392.

[92] Kolambkar YM, Peister A, Soker S, Atala A, Guldberg RE. Chondrogenic differentiation of amniotic fluid derived stem cells. J Mol Histol 2007; 38: 405–413.

[93] Peister A, Woodruff MA, Prince JJ, Gray DP, Hutmacher DW, Guldberg RE. Cell sourcing for bone tissue engineering: Amniotic fluid stem cells have a delayed, robust differentiation compared to mesenchymal stem cells. Stem Cell Res 2011; 7: 17–27.

[94] De Coppi P, Bartsch Jr G, Siddiqui MM, Xu T, Santos CC, Perin L, et al. Isolation of amniotic stem cell lines with potential for therapy. Nat Biotechnol 2007; 25: 100–106.

[95] Yu X, Wang N, Qiang R, Wan Q, Qin M, Chen Sh, et al. Human amniotic fluid stem cells possess the potential to differentiate into primordial follicle oocytes in vitro. Biol Reprod 2014; 90: 73–81.

[96] Zhang Q, Bu Sh, Sun J, Xu M, Yao X, He K, et al. Paracrine effects of human amniotic epithelial cells protect against chemotherapy-induced ovarian damage. Stem Cell Res Ther 2017; 8: 270.

[97] Magatti M, Vertua E, Cargnoni A, Silini A, Parolini O. The immunomodulatory properties of amniotic cells: The two sides of the coin. Cell Transplant 2018; 27: 31–44.

[98] Qiu Ch, Ge Zh, Cui W, Yu L, Li J. Human amniotic epithelial stem cells: A promising seed cell for clinical applications. Int J Mol Sci 2020; 21: 7730.

[99] Yu L. Human amniotic fluid-derived and amniotic membrane-derived stem cells. In: Zhao RC. Stem cells: Basics and clinical translation. China: Shanghai Jiao Tong University Press; 2015: 29–66.

[100] Cho Ch-KJ, Shan ShJ, Winsor EJ, Diamandis EP. Proteomics analysis of human amniotic fluid. Mol Cell Proteomics 2007; 6: 1406–1415.

[101] Da Sacco S, Sedrakyan S, Boldrin F, Giuliani S, Parnigotto P, Habibian R, et al. Human amniotic fluid as a potential new source of organ specific precursor cells for future regenerative medicine applications. J Urol 2010; 183: 1193–1200.

[102] Borlongan CV. Amniotic fluid as a source of engraftable stem cells. Brain Circ 2017; 3: 175.

[103] Moodley Y, Ilancheran S, Samuel Ch, Vaghjiani V, Atienza D, Williams ED, et al. Human amnion epithelial cell transplantation abrogates lung fibrosis and augments repair. Am J Respir Crit Care Med 2010; 182: 643–651.