A potential role for lysophosphatidylcholine in the delivery of long chain polyunsaturated fatty acids to the fetal circulation

The mechanisms of placental transfer of long chain polyunsaturated fatty acids are poorly understood, however fatty acid transporters in the syncytiotrophoblast microvillous (MVM) and basal plasma membrane (BM) are believed to be involved. Using LC-MS/MS and samples from normal term pregnant women, we found that the concentration of lysophosphatidylcholine-docosahexaenoyl (DHA-LPC) was 4-fold higher in umbilical vein plasma compared to maternal venous concentrations while conversely phosphatidylcholine (PC) containing DHA or arachidonic acid were higher in maternal circulation. Using primary human trophoblast cells incubated with DHA we show that DHA was highly incorporated into PC and LPC species in the placenta. Protein expression of Phosphatidylcholine Transfer Protein (PCTP) was 14-fold higher in MVM and the expression of MFSD2a, an LPC transporter, was 5-fold higher in BM than in MVM. Interestingly, BM MFSD2a expression was positively correlated with DHA-LPC in the umbilical vein. These findings suggest that syncytiotrophoblast takes up PC from the maternal circulation, as well as preferentially incorporating DHA into PC. Placental PC are converted to LPC forms, which are transported across the BM mediated by MFSD2a, with a strong selectivity for DHA.     

Ultrastructural development of chorioallantoic placenta in the Indian Miniopterus bat, Miniopterus schreibersii fuliginosus (Hodgson).

The chorioallantoic placental interhemal membrane of Miniopterus schreibersii fuliginosus has been described electron-microscopically. Morphologically there are three main types of placentae which develop in chronological sequence. They are (1) primary placenta, (2) secondary placenta and (3) tertiary placenta. In neural groove and limb-bud embryos the primary placenta consists of the following elements which separate the maternal and fetal circulations: (1) a continuous ectoplasmic layer, (2) intrasyncytial lamina, (3) syncytiotrophoblast, (4) cytotrophoblast, (5) basal lamina, (6) mesenchyme and (7) fetal endothelium. The primary placenta degenerates until term when it consists of a thin syncytiotrophoblastic layer resting on basal lamina. Mesenchyme does not show the presence of fetal capillaries. The secondary placenta is formed in early limb-bud embryos. The electron microscope has revealed that the placenta is of the endotheliomonochorial type and (1) consists of a well-developed maternal endothelium, (2) the trophoblast surrounding the maternal blood tubule is cellular, not syncytial as previously thought and the apical plasma membrane of these trophoblastic cells is in direct contact with the discontinuous interstitial membrane, (3) basal lamina, (4) mesenchyme and (5) fetal endothelium. Tertiary placenta at full term stage is of the hemodichorial type having the following elements: (1) thin ectoplasmic layer, (2) a thick intrasyncytial lamina, (3) syncytiotrophoblast, (4) cytotrophoblast, (5) basal lamina, (6) mesenchyme and (7) fetal endothelium. The definitive chorioallantoic placental barrier in this bat thus differs from the organization earlier proposed by Chari and Gopalakrishna [Proc. Indian Acad. Sci. 93: 463-483, 1984] on the basis of light-microscopic observations: (1) the absence of maternal endothelium in the primary placenta from the neural groove and early limb-bud embryos, (2) the existence of only cellular trophoblast in the secondary placenta throughout the gestation and (3) the presence of well-developed hemodichorial tertiary placenta is the unique feature of the interhemal membrane in higher Chiroptera.     

Pleiotropic Actions of Forskolin Result in Phosphatidylserine Exposure in Primary Trophoblasts

Forskolin is an extract of the Coleus forskholii plant that is widely used in cell physiology to raise intracellular cAMP levels. In the field of trophoblast biology, forskolin is one of the primary treatments used to induce trophoblastic cellular fusion. The syncytiotrophoblast (ST) is a continuous multinucleated cell in the human placenta that separates maternal from fetal circulations and can only expand by fusion with its stem cell, the cytotrophoblast (CT). Functional investigation of any aspect of ST physiology requires in vitro differentiation of CT and de novo ST formation, thus selecting the most appropriate differentiation agent for the hypothesis being investigated is necessary as well as addressing potential off-target effects. Previous studies, using forskolin to induce fusion in trophoblastic cell lines, identified phosphatidylserine (PS) externalization to be essential for trophoblast fusion and showed that widespread PS externalization is present even after fusion has been achieved. PS is a membrane phospholipid that is primarily localized to the inner-membrane leaflet. Externalization of PS is a hallmark of early apoptosis and is involved in cellular fusion of myocytes and macrophages. We were interested to examine whether PS externalization was also involved in primary trophoblast fusion. We show widespread PS externalization occurs after 72 hours when fusion was stimulated with forskolin, but not when stimulated with the cell permeant cAMP analog Br-cAMP. Using a forskolin analog, 1,9-dideoxyforskolin, which stimulates membrane transporters but not adenylate cyclase, we found that widespread PS externalization required both increased intracellular cAMP levels and stimulation of membrane transporters. Treatment of primary trophoblasts with Br-cAMP alone did not result in widespread PS externalization despite high levels of cellular fusion. Thus, we concluded that widespread PS externalization is independent of trophoblast fusion and, importantly, provide evidence that the common differentiation agent forskolin has previously unappreciated pleiotropic effects on trophoblastic cells.     

The PLAC1 protein localizes to membranous compartments in the apical region of the syncytiotrophoblast

PLAC1 is a trophoblast-specific gene that maps to a locus on the X-chromosome important to placental development. We have previously shown that PLAC1 gene expression is linked to trophoblast differentiation. The objective of this study was to define the localization of the PLAC1 polypeptide as a prerequisite to understanding its function. Polyclonal antibodies specific for the putative PLAC1 polypeptide were generated. The subcellular localization of PLAC1 in the trophoblast was examined by immunohistochemical analysis of human placenta complemented by immunoblot analysis of subcellular fractions. Brightfield immunohistochemical analysis of placental tissue indicated that the PLAC1 protein localizes to the differentiated syncytiotrophoblast in the apical region of the cell. Deconvlution immunofluorescence microscopy confirmed localization to the apical region of the syncytiotrophoblast. Its distribution included both intracellular compartments as well as loci in close association with the maternal-facing, microvillous brush border membrane (MVM). These findings were supported by immunoblot analysis of subcellular fractions. A 30 kDa band was associated with the microsomal fraction of placental lysates but not the mitochondrial, nuclear, or soluble fractions, suggesting PLAC1 is targeted to a membrane location. Plasma membranes were obtained from the fetal-facing, basal surface (BM) and the maternal-facing, MVM of the syncytiotrophoblast membrane. PLAC1 immunoreactivity was only detected in membrane fractions derived from the apical MVM consistent with immunohistochemical analyses. These data demonstrate that the PLAC1 protein is restricted primarily to the differentiated trophoblast, localizing to intracellular membranous compartment(s) in the apical region of the syncytiotrophoblast and associated with its apical, microvillous membrane surface.     

Lipid Rafts and Cytoskeletal Proteins in Placental Microvilli Membranes from Preeclamptic and IUGR Pregnancies

Intrauterine growth restriction (IUGR) and preeclampsia (PE) are leading causes of perinatal and maternal morbidity and mortality. Previously we reported the expression of lipid rafts in classical microvillous membrane (MVM) and light microvillous membrane (LMVM), two subdomains in apical membrane from the human placental syncytiotrophoblast (hSTB), which constitute the epithelium responsible for maternal–fetal transport. Here the aim was to study the raft and cytoskeletal proteins from PE and IUGR. Microdomains from MVM and LMVM were tested with raft markers (placental alkaline phosphatase, lipid ganglioside, and annexin 2) and a nonraft marker (hTf-R). No changes were detected with those markers in whole purified apical membranes in normal, PE, and IUGR pregnancies; however, their patterns of distribution in lipid rafts were different in PE and IUGR. Cholesterol depletion modified their segregation, confirming their presence in lipid rafts, although unlike normal placenta, in these pathologies there is only one type of microdomain. Additionally, the cytoskeleton proteins actin, ezrin, and cytokeratin-7 showed clear differences between normal and pathological membranes. Cytokeratin-7 expression decreased to 50% in PE, and the distribution between LMVM and MVM (~43 and 57%, respectively) changed in both PE and IUGR, in contrast with the asymmetrical enrichment obtained in normal LMVM (~62%). In conclusion, lipid rafts from IUGR and PE have different features compared to rafts from normal placentae, and this is associated with alterations in the expression and distribution of cytoskeletal proteins.     

Simultaneous preparation of paired, syncytial, microvillous and basal membranes from human placenta.

A method for the simultaneous preparation of microvillous and basal membrane vesicles from human placental syncytiotrophoblast is described. Mg2(+)-aggregated basal membranes are separated from microvillous membranes by low-speed centrifugation after initial homogenization and centrifugation steps. Microvillous membranes (MVM) are obtained from the low speed supernatant while basal membranes (BM) contained in the Mg2(+)-aggregated material are resuspended and further purified on a sucrose step gradient. MVM and BM prepared by this method were enriched 20-fold and 11-fold as determined by the membrane marker enzymes, alkaline phosphatase (MVM) and adenylate cyclase (BM). There was minimal cross-contamination of the two isolated plasma membrane fractions and the yields obtained were 26% (MVM) and 21% (BM) compared to the initial homogenate. The MVM and BM fractions were free from contamination by mitochondrial or lysosomal membranes and showed only minor contamination by microsomal membranes. The two membrane fractions were also tested for the presence of non-syncytial plasma membranes by electrophoretic immunoblotting. Contamination of both MVM and BM by fibroblast, endothelial, macrophage and cytotrophoblast plasma membranes amounted to less than 15% of the total membrane protein as determined by immunoblotting. Vesicle orientation, determined from the latency of specific concanavalin A binding, was 88 +/- 4% right-side out for MVM and 73 +/- 12% right-side out for BM. This simple preparative procedure produces a high yield of both MVM and BM from human placenta. The analytical data demonstrates that 'paired' MVM and BM fractions derived from the same placental tissue have a high purity in terms not only of contamination by intracellular membranes, but also in terms of contamination by non-syncytial plasma membranes.     

Villous cytotrophoblast regulation of the syncytial apoptotic cascade in the human placenta

 Villous trophoblast in the human placenta consists of a population of proliferating stem cells which differentiate and individually fuse into the syncytiotrophoblast. We studied the apoptotic cascade in this complex epithelial layer by immunohistochemical localization of Fas, FasL, Bcl-2, Mcl-1, pro-caspase-3 and caspase-3, T-cell-restricted intracellular antigen-related protein (TIAR), poly(ADP-ribose) polymerase (PARP), lamin B, topoisomerase IIα, and transglutaminase II in cryostat and paraffin-fixed tissue sections from normal human first-trimester and term placental villi. The relationship between the apoptotic cascade and syncytial fusion was studied by coincubation of intact villi with FITC-coupled annexin-V, to detect the phosphatidylserine flip, and propidium iodide, to detect plasma membrane permeability. The final events of the apoptotic cascade were studied by the TUNEL reaction and ultrastructural appearance of the trophoblast. The phosphatidylserine flip was identified in some of the villous cytotrophoblastic cells, but the presence of both Bcl-2 and Mcl-1 proteins presumably prevented continuation of the apoptotic cascade. The syncytiotrophoblast demonstrated heterogeneous findings, suggesting variable progression along the apoptotic cascade. In some areas Bcl-2 and Mcl-1 predominated, with preservation of the nuclear proteins PARP, lamin B, and topoisomerase IIα; in other areas, especially in and around syncytial sprouts, Bcl-2 and Mcl-1 were absent, accompanied by loss of nuclear proteins, presence of phosphatidylserine flip, and TUNEL positivity. These data suggest that the apoptotic cascade is initiated in the villous cytotrophoblast, which in turn promotes syncytial fusion. Donation of anti-apoptotic proteins into the syncytium, such as Bcl-2 and Mcl-1, focally inhibits further progression along this cascade. Completion of the apoptotic cascade takes place in and around syncytial sprouts, providing further evidence that these are the sites of trophoblast shedding into the maternal circulation. Accepted: 29 May 1998     

Development of the hemochorial maternal vascular spaces in the placenta through endothelial and vasculogenic mimicry

The maternal vasculature within the placenta in primates and rodents is unique because it is lined by fetal cells of the trophoblast lineage and not by maternal endothelial cells. In addition to trophoblast cells that invade the uterine spiral arteries that bring blood into the placenta, other trophoblast subtypes sit at different levels of the vascular space. In mice, at least five distinct subtypes of trophoblast cells have been identified which engage maternal endothelial cells on the arterial and venous frontiers of the placenta, but which also form the channel-like spaces within it through a process analogous to formation of blood vessels (vasculogenic mimicry). These cells are all large, post-mitotic trophoblast giant cells. In addition to assuming endothelial cell-like characteristics (endothelial mimicry), they produce dozens of different hormones that are thought to regulate local and systemic maternal adaptations to pregnancy. Recent work has identified distinct molecular pathways in mice that regulate the morphogenesis of trophoblast cells on the arterial and venous sides of the vascular circuit that may be analogous to specification of arterial and venous endothelial cells.     

Sex-specific responses in placental fatty acid oxidation,esterification and transfer capacity to maternal obesity

Fatty acid metabolism and oxidation capacity in the placenta, which likely affects the rate and composition of lipid delivered to the fetus remains poorly understood. Long chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), are critical for fetal growth and brain development. We determined the impact of maternal obesity on placental fatty acid oxidation, esterification and transport capacity by measuring PhosphatidylCholine (PC) and LysoPhosphatidylCholine (LPC) containing DHA by mass spectrometry in mother-placenta-baby triads as well as placental free carnitine and acylcarnitine metabolites in women with normal and obese pre-pregnancy BMI. Placental protein expression of enzymes involved in beta-oxidation and esterification pathways, MFSD2a (lysophosphatidylcholine transporter) and OCTN2 (carnitine transporter) expression in syncytiotrophoblast microvillous (MVM) and basal (BM) membranes were determined by Western Blot. Maternal obesity was associated with decreased umbilical cord plasma DHA in LPC and PC fractions in male, but not female, fetuses. Basal membrane MFSD2a protein expression was increased in placenta of males of obese mothers. In female placentas, despite an increased MVM OCTN2 expression, maternal obesity was associated with a reduced MUFA-carnitine levels and increased esterification enzymes. We speculate that lower DHA-PL in fetal circulation of male offspring of obese mothers, despite a significant increase in transporter expression for LPC-DHA, may lead to low DHA needed for brain development contributing to neurological consequences that are more prevalent in male children. Female placentas likely have reduced beta-oxidation capacity and appear to store FA through greater placental esterification, suggesting impaired placenta function and lipid transfer in female placentas of obese mothers.     

Glycogen-containing cells in the maternal and embryonic portions of the placenta in the rat and the common vole Microtus subarvalis

Differentiation sequences and further transfiguration of glycogen-rich cells during placenta development were investigated for the rat and field vole Microtus subarvalis (11-20 day gestation). The presence of glycogen is a characteristic feature of decidual cells located in the region of lateral sinusoids, as well as of metrial gland cells, secondary giant trophoblast cells and trophoblast cells in the connective zone of placenta. Glycogen-containing metrial gland cells and trophoblast cells of connective zone of placenta are found to underlie the layer of tertiary giant trophoblast cells that cover the wall of the central arteria. Thus, both maternal and embryo-derived glycogen-containing cells always accompany the tertiary giant trophoblast cells that penetrate deeply into the maternal part of placenta but do not contain glycogen. In the field vole placenta the cells of peripheral trophoblast subpopulation of the connective zone of placenta attaching to the decidua basalis are stained by PAS-reaction more intensely than deeply situated ones. These data, as well as other phenomena revealed here, show that maternal and trophoblastic cells attaching to each other in placenta contain, as a rule glycogen. Glycogen cells in rat placenta and trophoblast cells of peripheral subpopulation of connective zone of placenta are similar in many respects. In this connection, a possible protective role of glycogen-containing cells, that probably favour the co-existence of maternal and embryo-derived cells in placenta, is discussed.     

Polymerization of insulin‐like growth factor‐binding protein‐1 (IGFBP‐1) potentiates IGF‐I actions in placenta

Insulin‐like growth factor (IGF)‐binding protein‐1 (IGFBP‐1), the main secretory protein of decidua that binds to IGFs and has been shown to inhibit or stimulate IGFs' bioactivities. Polymerization, one of the posttranslational modifications of IGFBP‐1, has been shown to lead to loss of inhibiting effect of IGFBP‐1 on IGF‐I actions. The current studies were undertaken to elucidate the effects of steroid hormones on IGFBP‐1 polymerization in trophoblast cell cultures. Placental tissues were obtained during legal, elective procedures of termination of pregnancy performed between 7 and 10 weeks of gestation, and primary trophoblast cells were separated. IGFBP‐1 polymerization was analyzed by SDS–PAGE and immunoblotting. IGFBP‐1 was polymerized when IGFBP‐1 was added to trophoblast cell cultures. Polymerization of IGFBP‐1 was inhibited by the addition of anti‐tissue transglutaminase antibody into the culture media. There was an increase in the intensity of polymerized IGFBP‐1 bands with the addition of medroxyprogesterone acetate (MPA), while no such difference was observed upon treatment with estradiol. MPA also increased the expression of tissue transglutaminase on trophoblast cell membranes. IGF‐I stimulated trophoblast cell migration, while IGFBP‐1 inhibited this IGF‐I‐induced trophoblast response. Addition of MPA attenuated the inhibitory effects of IGFBP‐1 on IGF‐I‐induced trophoblast cell migration. IGFBP‐1 was polymerized by tissue transglutaminase on the cell surface of trophoblasts, and MPA increased tissue transglutaminase expression on the cell surface and facilitated IGFBP‐1 polymerization. These results suggest that progesterone might facilitate polymerization of decidua‐secreted IGFBP‐1 and increase IGF‐I actions at feto‐maternal interface, thereby stimulating trophoblast invasion of maternal uterus. J. Cell. Physiol. 226: 434–439, 2011. © 2010 Wiley‐Liss, Inc.     

Comparative electron microscopy of chorio-allantoic placental barrier in some Indian Chiroptera

In the present study the comparative ultrastructure of the definitive chorio-allantoic placental barrier has been studied in considerable detail in six species of bats, representing six different families and both suborders of Chiroptera, by electron microscopy, and these species illustrate different kinds of interhaemal membranes met with among bats. The definitive chorio-allantoic placenta of Rousettus leschenaulti is haemodichorial, since the syncytiotrophoblast and cytotrophoblast layers are present to term. The fine structure of the placental barrier in the labyrinth of the definitive placenta of Rhinopoma hardwickei hardwickei is essentially endotheliomonochorial due to the presence of a single layer of cytotrophoblast and maternal endothelial cells. The placenta of Taphozous melanopogon, examined electron-microscopically in the present study, shows a thick maternal endothelium, a continuous interstitial membrane and the presence of a single layer of syncytiotrophoblast. The placenta of Megaderma comprises a typical endotheliochorial labyrinth and the presence of two layers of trophoblast. In Rhinolophus rouxi, the mature placenta during advanced pregnancy resembles that of Megaderma, its labyrinth containing large maternal capillaries with maternal endothelial cells and the two layers of trophoblast. Finally, the placental barrier of Hipposideros fulvus fulvus is haemodichorial due to the presence of two layers of trophoblast and the absence of maternal endothelial cells.     

The organization of actin filaments in human placental villi

The surface of the syncytial trophoblast of the human placenta is covered by a microvillous (brush) border that is in direct contact with maternal blood. Because of this location, it is the site of a variety of transport, enzymatic and receptor activities vital to many placental functions. The organization of the brush border as well as other features of placental villus organization may well be influenced by the distribution of cytoplasmic actin filaments. In order to determine the distribution of actin filaments in human placenta, small pieces of villi were briefly fixed in glutaraldehyde, permeabilized with saponin, and incubated in solutions containing subfragment 1 of myosin (S1). After S1 decoration of actin filaments, tissue was fixed in glutaraldehyde containing tannic acid in order to better visualize the polarity of the filaments, and prepared for electron microscopic examination. The microvilli each contained a core of actin filaments running from the tip of the microvillus to the apical cytoplasm. Most of the actin filaments displayed a distinct polarity, with the S1 arrowheads pointing away from the microvillar tips. These filaments extended only a short distance into the apical cytoplasm. There appeared to be another group of actin filaments in a matlike arrangement in the apical cytoplasm. Coated pits and vesicles were often observed between the microvilli. There appeared to be no clear association between the coated pits and decorated actin filaments, but this was difficult to establish with certainty because of the close proximity of the microvilli. Bundles of actin filaments were sometimes observed near the basal cell surface of the syncytial trophoblast, and in pericytes and capillary endothelial cells in the cores of the villi.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nitric oxide synthase activity in human trophoblast, term placenta and pregnant myometrium

To investigate the possible role of nitric oxide (NO) produced locally or intramurally in the quiescence of the pregnant myometrium, nitric oxide synthase (NOS) activity was measured in samples from first trimester (villous, and non villous-trophoblast), term placenta and pregnant myometrium. Trophoblast tissue was obtained from psychosocial termination of pregnancy (9 – 12 weeks' gestation) whereas placenta and myometrium, from the same patient, at deliveries by Caesarean section. NOS activity was measured in both cytosolic and particulate fractions by the formation of ¹⁴C-citrulline from ¹⁴C-arginine. Western immunoblotting was used to identify the endothelial NOS (eNOS) and neuronal (nNOS) isoforms. The activity of NOS in particulate fractions from all preparations was considerably higher than the cytosolic fractions. Activity in all fractions except the myometrium was highly Ca-dependent. More than 50% of particulate NOS from the myometrium was Ca-independent. NOS activity was highest in the villous trophoblast and there was a significant difference between the villous and non-villous trophoblast. In placenta and myometrium, NOS was 2–4 fold and 20–28-fold lower than the villous trophoblast, respectively. Western blot analysis showed clearly eNOS in the particulate fraction and a weak eNOS band in the cytosolic fractions, whereas nNOS was not detectable in any of the fractions. In view of the marginal activity of NOS in the myometrium, NO produced by the trophoblast and placenta could play a significant role in maintaining uterine quiescence by paracrine effect.     

Transglutaminase 2 Expression Is Increased as a Function of Malignancy Grade and Negatively Regulates Cell Growth in Meningioma

Most meningiomas are benign, but some clinical-aggressive tumors exhibit brain invasion and cannot be resected without significant complications. To identify molecular markers for these clinically-aggressive meningiomas, we performed microarray analyses on 24 primary cultures from 21 meningiomas and 3 arachnoid membranes. Using this approach, increased transglutaminase 2 (TGM2) expression was observed, which was subsequently validated in an independent set of 82 meningiomas by immunohistochemistry. Importantly, the TGM2 expression level was associated with increasing WHO malignancy grade as well as meningioma recurrence. Inhibition of TGM2 function by siRNA or cystamine induced meningioma cell death, which was associated with reduced AKT phosphorylation and caspase-3 activation. Collectively, these findings suggest that TGM2 expression increases as a function of malignancy grade and tumor recurrence and that inhibition of TGM2 reduces meningioma cell growth.     

Role of MDR1 and MRP1 in trophoblast cells,elucidated using retroviral gene transfer

Natural differences in expression and retroviral transduction techniques were used to test the hypothesis that MDR1 P-glycoprotein (P-gp) and MRP1 (multidrug resistance-related protein) contribute to xenobiotic handling by placental trophoblast. RT-PCR and Western blotting in placenta, primary cytotrophoblast cell cultures, and BeWo, JAr, and JEG choriocarcinoma cell lines showed that MRP1 was ubiquitously expressed, whereas MDR1 was absent or minimally expressed in BeWo and JEG cell lines. In syncytiotrophoblast, P-gp was localized predominantly to the microvillous, maternal facing plasma membrane, and MRP1 to the basal, fetal facing plasma membrane. Functional studies showed that cyclosporin A-sensitive accumulation of [³H]vinblastine by cells containing both transport proteins was significantly different from those expressing predominantly MRP1. Retroviral gene transfer of MDR1 to BeWo cells confirmed that this difference was due to the relative expression of MDR1. Therefore, both P-gp and MRP1 contribute to xenobiotic handling by the trophoblast. Localization of P-gp to the microvillous membrane suggests an essential role in preventing xenobiotic accumulation by the syncytiotrophoblast and, therefore, in protecting the fetus. placenta; multidrug resistance; xenobiotic     

Tissue transglutaminase_variant 2-transduced mesenchymal stem cells and their chondrogenic potential

As cartilage is incapable of self-healing upon severe degeneration because of the lack of blood vessels, cartilage tissue engineering is gaining importance in the treatment of cartilage defects. This study was designed to improve cartilage tissue regeneration by expressing tissue transglutaminase variant 2 (TGM2_v2) in mesenchymal stem cells (MSC) derived from bone marrow of rats. For this purpose, rat MSCs transduced with TGM2_v2 were grown and differentiated on three-dimensional polybutylene succinate (PBSu) and poly-l -lactide (PLLA) blend scaffolds. The transduced cells could not only successfully express the short form transglutaminase-2, but also deposited the protein onto the scaffolds. In addition, they could spontaneously produce cartilage-specific proteins without any chondrogenic induction, suggesting that TGM2_v2 expression provided the cells the ability of chondrogenic differentiation. PBSu:PLLA scaffolds loaded with TGM2_v2 expressing MSCs could be used in repair of articular cartilage defects.