Microvesicles Derived from Human Wharton's Jelly Mesenchymal Stem Cells Promote Human Renal Cancer Cell Growth and Aggressiveness through Induction of Hepatocyte Growth Factor

In our previous study, microvesicles (MVs) released from human Wharton''s jelly mesenchymal stem cells (hWJ-MSCs) retard the growth of bladder cancer cells. We would like to know if MVs have a similar effect on human renal cell carcinoma (RCC). By use of cell culture and the BALB/c nu/nu mice xeno-graft model, the influence of MVs upon the growth and aggressiveness of RCC (786-0) was assessed. Cell counting kit-8 (CCK-8) assay, incidence of tumor, tumor size, Ki-67 or TUNEL staining was used to evaluate tumor cell growth in vitro or in vivo. Flow cytometry assay (in vitro) or examination of cyclin D1 expression (in vivo) was carried out to determine the alteration of cell cycle. The aggressiveness was analyzed by Wound Healing Assay (in vitro) or MMP-2 and MMP-9 expression (in vivo). AKT/p-AKT, ERK1/2/p-ERK1/2 or HGF/c-MET expression was detected by real-time PCR or western blot. Our data demonstrated that MVs promote the growth and aggressiveness of RCC both in vitro and in vivo. In addition, MVs facilitated the progression of cell cycle from G_0/1 to S. HGF expression in RCC was greatly induced by MVs, associated with activation of AKT and ERK1/2 signaling pathways. RNase pre-treatment abrogated all effects of MVs. In summary, induction of HGF synthesis via RNA transferred by MVs activating AKT and ERK1/2 signaling is one of crucial contributors to the pro-tumor effect.     

Autologous cell therapy for cisplatin-induced acute kidney injury by using non-expanded adipose tissue-derived cells

Abstract Background aims. Recent studies have demonstrated that cultured mesenchymal stromal cells derived from adipose tissue are useful for regenerative cell therapy. The stromal vascular fraction (SVF) can be obtained readily without culturing and may be clinically applicable. We investigated the therapeutic effects of SVF and used it in the treatment of acute kidney injury (AKI). Methods. Liposuction aspirates were obtained from healthy donors who had provided written informed consent. We harvested the SVF and determined the growth factor secretion and anti-apoptotic ability with conditioned medium. To investigate the effect of SVF on AKI, cisplatin was injected into rats and SVF was administrated into the subcupsula of the kidney. Results. Both human and rat SVF cells secreted vascular endothelial growth factor-A (VEGF) and hepatocyte growth factor (HGF). Human SVF-conditioned media had an anti-apoptotic effect, which was inhibited by anti-HGF antibody (Ab) but not by anti-VEGF Ab. In vivo, SVF significantly ameliorated renal function, attenuated tubular damage and increased the cortical blood flow speed. In the SVF-treated group, VEGF levels in the cortex and HGF levels in both the cortex and medulla, especially tubules in the medulla, were significantly higher. Immunostaining revealed that SVF cells expressing VEGF and HGF and remained in the subcapsule on day 14. Conclusions. The present study demonstrates that a subcapsular injection of non-expanded SVF cells ameliorates rat AKI, and that the mechanism probably involves secretion of renoprotective molecules. Administration of human SVF may be clinically applicable and useful as a novel autologous cell therapy against kidney diseases.     

大鼠心肌虚血再灌流后肝细胞再生因子的表达变化

肝细胞再生因子（hepatocyte growth factor, HGF）对多种细胞都具有促进增殖及运动、抗凋亡的作用,对组织器官的发育形成也起到重要作用．在肝脏、肾脏、肺、心脏等器官受损之后的修复过程中,有积极的促进再生的作用．本研究采用了心虚血再灌流大鼠模型,发现心肌细胞受损伤后 6 h 血清中HGF水平显著增高．在比较了肾脏、肺、肝脏、脾脏等组织提取液中HGF的含量之后,发现心虚血再灌流手术后,肾脏、肺、肝脏中HGF的含量变化不明显,而脾脏的提取液中HGF的含量增加显著．对脾脏组织的连续切片进行HGF与血管内皮细胞的特异性标志物von Willanbrand Factor (vWF)免疫组织化学染色研究,发现手术后脾脏中产生HGF的细胞主要为血管内皮细胞．此项研究首次阐明组织器官受损后,远端组织器官的血管内皮细胞能够增加HGF的合成和分泌,增加的HGF通过体液循环到达受损组织器官,促进其修复再生．     

Microvesicles derived from mesenchymal stem cells enhance survival in a lethal model of acute kidney injury

Several studies demonstrated that treatment with mesenchymal stem cells (MSCs) reduces cisplatin mortality in mice. Microvesicles (MVs) released from MSCs were previously shown to favor renal repair in non lethal toxic and ischemic acute renal injury (AKI). In the present study we investigated the effects of MSC-derived MVs in SCID mice survival in lethal cisplatin-induced AKI. Moreover, we evaluated in vitro the effect of MVs on cisplatin-induced apoptosis of human renal tubular epithelial cells and the molecular mechanisms involved. Two different regimens of MV injection were used. The single administration of MVs ameliorated renal function and morphology, and improved survival but did not prevent chronic tubular injury and persistent increase in BUN and creatinine. Multiple injections of MVs further decreased mortality and at day 21 surviving mice showed normal histology and renal function. The mechanism of protection was mainly ascribed to an anti-apoptotic effect of MVs. In vitro studies demonstrated that MVs up-regulated in cisplatin-treated human tubular epithelial cells anti-apoptotic genes, such as Bcl-xL, Bcl2 and BIRC8 and down-regulated genes that have a central role in the execution-phase of cell apoptosis such as Casp1, Casp8 and LTA. In conclusion, MVs released from MSCs were found to exert a pro-survival effect on renal cells in vitro and in vivo, suggesting that MVs may contribute to renal protection conferred by MSCs.     

Lipocalin 2 enhances mesenchymal stem cell-based cell therapy in acute kidney injury rat model

Acute kidney injury (AKI) is one of the most common health-threatening diseases in the world. There is still no effective medical treatment for AKI. Recently, Mesenchymal stem cell (MSC)-based therapy has been proposed for treatment of AKI. However, the microenvironment of damaged kidney tissue is not favorable for survival of MSCs which would be used for therapeutic intervention. In this study, we genetically manipulated MSCs to up-regulate lipocalin-2 (Lcn2) and investigated whether the engineered MSCs (MSC-Lcn2) could improve cisplatin-induced AKI in a rat model. Our results revealed that up-regulation of Lcn2 in MSCs efficiently enhanced renal function. MSC Lcn2 up-regulates expression of HGF, IGF, FGF and VEGF growth factors. In addition, they reduced molecular biomarkers of kidney injury such as KIM-1 and Cystatin C, while increased the markers of proximal tubular epithelium such as AQP-1 and CK18 following cisplatin-induced AKI. Overall, here we over-expressed Lcn2, a well-known cytoprotective factor against acute ischemic renal injury, in MSCs. This not only potentiated beneficial roles of MSCs for cell therapy purposes but also suggested a new modality for treatment of AKI.     

The alleviation of acute and chronic kidney injury by human Wharton's jelly-derived mesenchymal stromal cells triggered by ischemia-reperfusion injury via an endocrine mechanism

Background aimsThe effects of human Wharton's jelly-derived mesenchymal stromal cells (WJ-MSC) on acute and chronic kidney injury induced by ischemia-reperfusion injury (IRI) were assessed.MethodsWJ-MSC were injected intravenously immediately after solitary kidney ischemia for 45 min. Cells were labeled with 5-bromo-2′deoxy-uridine (BrdU) for tracing in vivo. At 48 h post-IRI, serum creatinine and blood urea nitrogen (BUN) were measured. Tubular cell proliferation and apoptosis as well as activation of the Akt signal were identified by immunostaining. Real-time polymerase chain reaction (PCR) was employed to determine gene expression of inflammation-related cytokines and hepatocyte growth factor (HGF). Levels of human HGF were assayed by enzyme-linked immunosorbant assay (ELISA). Twenty-two weeks later, renal fibrosis was assessed by Masson's tri-chrome staining, collagen content and α-smooth muscle actin (α-SMA) staining.ResultsThere was no sign of labeled cells residing in the damaged kidney. Acute renal dysfunction elicited by IRI was considerably improved by WJ-MSC, in parallel with a stronger proliferative response and less apoptotic events. Additionally, phosphoAkt staining in injured tubular cells was substantially intensified. Cell treatment also caused a remarkable up-regulation of kidney interleukin (IL)-10, heme oxygenase (HO)-1 and HGF expression. Human HGF was detected in cell supernatants and the serum of cell-infused rats. Moreover, IRI-initiated fibrosis was abrogated by cell therapy, coincident with function amelioration.ConclusionsWJ-MSC alleviate acute kidney injury, thereby rescuing the ensuing fibrotic lesions in an endocrine manner. The Akt signal in impaired tubular cells is reinforced by WJ-MSC, facilitating cell resistance to apoptosis and cell proliferation. HGF, either delivered or induced by WJ-MSC, is an important contributor.     

Mitochondrial transplantation ameliorates ischemia/reperfusion-induced kidney injury in rat

No real therapeutic modality is currently available for Acute kidney injury (AKI) and if any, they are mainly supportive in nature. Therefore, developing a new therapeutic strategy is crucial. Mitochondrial dysfunction proved to be a key contributor to renal tubular cell death during AKI. Thus, replacement or augmentation of damaged mitochondria could be a proper target in AKI treatment. Here, in an animal model of AKI, we auto-transplanted normal mitochondria isolated from healthy muscle cells to injured kidney cells through injection to renal artery. The mitochondria transplantation prevented renal tubular cell death, restored renal function, ameliorated kidney damage, improved regenerative potential of renal tubules, and decreased ischemia/reperfusion-induced apoptosis. Although further studies including clinical trials are required in this regard, our findings suggest a novel therapeutic strategy for treatment of AKI. Improved quality of life of patients suffering from renal failure and decreased morbidity and mortality rates would be the potential advantages of this therapeutic strategy.     

Marked induction of hepatocyte growth factor mRNA in intact kidney and spleen in response to injury of distant organs.

Hepatocyte growth factor (HGF) is a potent mitogen for various epithelial cells, including mature hepatocytes and renal tubular cells. Here, HGF mRNA was found to be markedly increased in non-injured kidney and spleen, when the liver or kidney in rats was injured by 70% partial hepatectomy or unilateral nephrectomy. HGF mRNA increased to 3-4 fold higher level than the normal in the kidney and spleen as well as in the remnant liver after partial hepatectomy. Similarly, HGF mRNA markedly increased in the spleen as well as in the remnant kidney after unilateral nephrectomy. These results suggest that the onset of injury to the liver or kidney may be recognized by distal non-injured organs by the signalling of a humoral factor and that HGF derived from these organs may be involved in the regeneration of liver or kidney, through an endocrine mechanism.     

Cell Atavistic Transition: Paired Box 2 Re-Expression Occurs in Mature Tubular Epithelial Cells during Acute Kidney Injury and Is Regulated by Angiotensin II

The regeneration of tubular epithelial cells (TECs) after acute kidney injury (AKI) is crucial for the recovery of renal structure and function. The mechanism by which quiescent TECs re-obtain a potential to regenerate remains unknown. In this study, we observed a transient re-expression of embryonic gene Paired box 2 (Pax2) in adult rat TECs in vivo during ischemia-reperfusion induced AKI and most Pax2 positive TECs co-expressed kidney injury molecule-1 (KIM-1), a tubular injury marker. The re-expression of Pax2 was accompanied by increased levels of intrarenal Angiotensin II, which is a crucial injury factor of AKI. Furthermore, we also found a temporary re-expression of Pax2 in NRK-52E cells under the stimulation of Angiotensin II. This stimulatory effect could be blocked by PD123319 (Angiotensin II type 2 receptor (AT2R) inhibitor) and AG490 (Janus Kinase 2 (JAK2) inhibitor). As Pax2 is essential for the phenotypic conversion from mesenchymal stem cells to TECs during kidney development, we proposed that the re-expression of Pax2 in mature TECs may be an indicator of “atavistic” transition which mimics but reverses the processes of development of TECs. This could be proved by that a progenitor marker, CD24, was also found to be transiently expressed shortly after the expression of Pax2 in NRK-52E cells stimulated with Angiotensin II. The expression of CD24 was also suppressed by PD123319 and AG490. Moreover, knockdown of Pax2 by RNA interference could significantly reduce the expression of CD24 in NRK-52E cells stimulated with Angiotension II. Those findings suggest that mature TECs can trans-differentiate into progenitor-like cells by “atavistic transition”, which may participate in the recovery of tissue structure and Pax2 may play a pivotal role in this process. That might have important implications for further understanding of tubular regeneration after injury.     

N-WASP and WAVE2 acting downstream of phosphatidylinositol 3-kinase are required for myogenic cell migration induced by hepatocyte growth factor

During skeletal muscle regeneration caused by injury, muscle satellite cells proliferate and migrate toward the site of muscle injury. This migration is mainly induced by hepatocyte growth factor (HGF) secreted by intact myofibers and also released from injured muscle. However, the intracellular machinery for the satellite cell migration has not been elucidated. To examine the mechanisms of satellite cell migration, we utilized satellite cell-derived mouse C2C12 skeletal muscle cells. HGF induced reorganization of actin cytoskeleton to form lamellipodia in C2C12 myoblasts. HGF treatment facilitated both nondirectional migration of the myoblasts in phagokinetic track assay and directional chemotactic migration toward HGF in a three-dimensional migration chamber assay. Endogenous N-WASP and WAVE2 were concentrated in the lamellipodia at the leading edge of the migrating cells. Moreover, exogenous expression of wild-type N-WASP or WAVE2 promoted lamellipodial formation and migration. By contrast, expression of the dominant-negative mutant of N-WASP or WAVE2 and knockdown of N-WASP or WAVE2 expression by the RNA interference prevented the HGF-induced lamellipodial formation and migration. When the cells were treated with LY294002, an inhibitor of phosphatidylinositol 3-kinase, the HGF-induced lamellipodial formation and migration were abrogated. These results imply that both N-WASP and WAVE2, which are activated downstream of phosphati-dylinositol 3-kinase, are required for the migration through the lamellipodial formation of C2C12 cells induced by HGF.     

Hepatocyte growth factor is a potent mitogen for cultured rabbit renal tubular epithelial cells.

Hepatocyte growth factor (HGF), which is a potent growth factor of adult rat hepatocytes in primary culture, also strongly stimulated DNA synthesis of rabbit renal tubular epithelial cells in secondary culture. Its mitogenic activity was dose-dependent, being detectable at 3 ng/ml and maximal at 30 ng/ml. Over 20% of the cells were shifted to the S-phase by HGF alone, judging by the labeling index. HGF had additive effects with EGF, acidic fibroblast growth factor (a-FGF), and insulin. Transforming growth factor-beta 1 (TGF-beta 1) strongly inhibited DNA synthesis of renal tubular cells stimulated by HGF. The growth of renal tubular epithelial cells was also regulated by cell density: DNA synthesis stimulated by HGF was high at lower cell density and was strongly suppressed at high cell density. These results suggest that HGF may act as a renotropic factor in compensatory renal growth or renal regeneration in vivo.     

cMet agonistic antibody attenuates apoptosis in ischaemia-reperfusion–induced kidney injury

Acute kidney injury (AKI) is a very common complication with high morbidity and mortality rates and no fundamental treatment. In this study, we investigated whether the hepatocyte growth factor (HGF)/cMet pathway is associated with the development of AKI and how the administration of a cMet agonistic antibody (Ab) affects an AKI model. In the analysis using human blood samples, cMet and HGF levels were found to be significantly increased in the AKI group, regardless of underlying renal function. The administration of a cMet agonistic Ab improved the functional and histological changes after bilateral ischaemia-reperfusion injury. TUNEL-positive cells and Bax/Bcl-2 ratio were also reduced by cMet agonistic Ab treatment. In addition, cMet agonistic Ab treatment significantly increased the levels of PI3K, Akt and mTOR. Furthermore, after 24 hours of hypoxia induction in human proximal tubular epithelial cells, treatment with the cMet agonistic Ab also showed dose-dependent antiapoptotic effects similar to those of the recombinant HGF treatment. Even when the HGF axis was blocked with a HGF-blocking Ab, the cMet agonistic Ab showed an independent dose-dependent antiapoptotic effect. In conclusion, cMet expression is associated with the occurrence of AKI. cMet agonistic Ab treatment attenuates the severity of AKI through the PI3K/Akt/mTOR pathway and improves apoptosis. cMet agonistic Ab may have important significance for the treatment of AKI.     

Expressions of receptor gene for hepatocyte growth factor in kidney after unilateral nephrectomy and renal injury.

The renal expressions of the receptor gene (c-met) for hepatocyte growth factor (HGF) were examined in unilateral nephrectomy (UNX), renal ischemia or folic acid administration. The levels of c-met mRNA were increased rapidly in all rat models at 6h after the operations. On the other hand, the expression of c-met mRNA in a kidney cell line (MDCK cells) was down-regulated for 8 h after HGF addition, indicating that c-met mRNA induction in rat models may be independent of the stimulated production of HGF. The stimulated expression of c-met in these models suggest that HGF may play an important role in renal hypertrophy after UNX and regeneration after ischemic or nephrotoxic injury.     

Mesenchymal-like progenitors derived from human embryonic stem cells promote recovery from acute kidney injury via paracrine actions

Background aimsThe engraftment of mesenchymal stem cells (MSCs) is reported to promote recovery of renal function in animal models of acute kidney injury (AKI). However, it is unknown whether mesenchymal-like progenitors (MPs) derived from human embryonic stem cells (hESCs) can mediate similar therapeutic effects. We investigated the responses of recipient renal tissue to engraftment of hESC-MPs and underlying mechanisms of these effects.MethodsWe measured blood urea nitrogen and creatinine levels of AKI mice with hESC-MPs transplantation and control mice. We performed renal morphology analysis by immunohistochemistry and electron microscopy to confirm the renoprotective effects of engrafted hESC-MPs. Proliferation, apoptosis and gene expression of tubular cells were also monitored by immunohistochemistry and real-time quantitative polymerase chain reaction to investigate the mechanisms that occurred.ResultsAfter transplantation of hESC-MPs into mice with cisplatin-induced AKI, improvements in renal function and recovery from tubular epithelial cell injury were observed. Engrafted hESC-MPs were localized to areas of injured kidney 5 days after cisplatin induction, where they promoted tubular cell proliferation and decreased kidney cell apoptosis. The beneficial effect was further confirmed by the capability of the engrafted cells to up-regulate renal gene expression of anti-inflammatory cytokines and pro-survival cytokines. Meanwhile, infusion of these cells reduced renal gene expression of pro-inflammatory cytokines and monocyte chemotactic protein-1, a chemokine that stimulates monocyte and macrophage infiltration.ConclusionsOur results show that infused hESC-MPs may promote recovery from AKI by regulating related cytokines.     

Potential advantages of acute kidney injury management by mesenchymal stem cells

Mesenchymal stem cells are currently considered as a promising tool for therapeutic application in acute kidney injury (AKI) management. AKI is characterized by acute tubular injury with rapid loss of renal function. After AKI, inflammation, oxidative stress and excessive deposition of extracellular matrix are the molecular events that ultimately cause the end-stage renal disease. Despite numerous improvement of supportive therapy, the mortality and morbidity among patients remain high. Therefore, exploring novel therapeutic options to treat AKI is mandatory. Numerous evidence in animal models has demonstrated the capability of mesenchymal stem cells (MSCs) to restore kidney function after induced kidney injury. After infusion, MSCs engraft in the injured tissue and release soluble factors and microvesicles that promote cell survival and tissue repairing. Indeed, the main mechanism of action of MSCs in tissue regeneration is the paracrine/endocrine secretion of bioactive molecules. MSCs can be isolated from several tissues, including bone marrow, adipose tissue, and blood cord; pre-treatment procedures to improve MSCs homing and their paracrine function have been also described. This review will focus on the application of cell therapy in AKI and it will summarize preclinical studies in animal models and clinical trials currently ongoing about the use of mesenchymal stem cells after AKI.     

Renotropic functions of hepatocyte growth factor in renal regeneration after unilateral nephrectomy.

Hepatocyte growth factor (HGF), a most potent growth factor for mature hepatocytes may act as a trigger for liver regeneration. We reported that HGF strongly stimulates DNA synthesis of rabbit renal tubular cells in secondary culture (Igawa, T., Kanda, S., Kanetake, H., Saitoh, Y., Ichihara, A., Tomita, Y., and Nakamura, T. (1991) Biochem. Biophys. Res. Commun. 174, 831-838). To investigate whether or not HGF is involved in renal regeneration, we examined changes in HGF mRNA, HGF activity, and HGF receptor in the rat kidney following unilateral nephrectomy or treatment with carbon tetrachloride (CCl4). In the intact kidney, the HGF mRNA increased markedly reaching a maximum 6 h after unilateral nephrectomy, followed by an increase of HGF activity at 12 h after the surgery. The marked increase in HGF mRNA and HGF activity was also found in the kidney of rats treated with CCl4. Results of in situ hybridization suggested that cells producing HGF in the kidney are endothelial cells. The number of HGF receptors on renal plasma membranes decreased to 30% of the normal value 12 h after unilateral nephrectomy, with no change in the Kd value. The HGF receptor was greatly diminished 24 h after the operation, and recovery to 60% of the normal level was evident 1 week after the operation. Because the decrease in HGF binding may result from internalization of the HGF receptor, the HGF may bind to its receptor in vivo and act as a mitogen for renal epithelial cells. HGF may function as a renotropic factor during renal regeneration after kidney injury.     

DNA damage response in renal ischemia–reperfusion and ATP-depletion injury of renal tubular cells

Renal ischemia–reperfusion leads to acute kidney injury (AKI) that is characterized pathologically by tubular damage and cell death, followed by tubular repair, atrophy and interstitial fibrosis. Recent work suggested the possible presence of DNA damage response (DDR) in AKI. However, the evidence is sketchy and the role and regulation of DDR in ischemic AKI remain elusive. In this study, we demonstrated the induction of phosphorylation of ATM, H2AX, Chk2 and p53 during renal ischemia–reperfusion in mice, suggesting DDR in kidney tissues. DDR was also induced in vitro during the recovery or “reperfusion” of renal proximal tubular cells (RPTCs) after ATP depletion. DDR in RPTCs was abrogated by supplying glucose to maintain ATP via glycolysis, indicating that the DDR depends on ATP depletion. The DDR was also suppressed by the general caspase inhibitor z-VAD and the overexpression of Bcl-2, supporting a role of apoptosis-associated DNA damage in the DDR. N-acetylcysteine (NAC), an antioxidant, suppressed the phosphorylation of ATM and p53 and, to a less extent, Chk2, but NAC increased the phosphorylation and nuclear foci formation of H2AX. Interestingly, NAC increased apoptosis, which may account for the observed H2AX activation. Ku55933, an ATM inhibitor, blocked ATM phosphorylation and ameliorated the phosphorylation of Chk2 and p53, but it increased H2AX phosphorylation and nuclear foci formation. Ku55933 also increased apoptosis in RPTCs following ATP depletion. The results suggest that DDR occurs during renal ischemia–reperfusion in vivo and ATP-depletion injury in vitro. The DDR is partially induced by apoptosis and oxidative stress-related DNA damage. ATM, as a sensor in the DDR, may play a cytoprotective role against tubular cell injury and death.     

Growth factor supplemented matrigel improves ectopic skeletal muscle formation--a cell therapy approach

Following damage to skeletal muscle, satellite cells become activated, migrate towards the injured area, proliferate, and fuse with each other to form myotubes which finally mature into myofibers. We tested a new approach to muscle regeneration by incorporating myoblasts, with or without the exogenous growth factors bFGF or HGF, into three-dimensional gels of reconstituted basement membrane (matrigel). In vitro, bFGF and HGF induced C2C12 myoblast proliferation and migration and were synergistic when used together. In vivo, C2C12 or primary i28 myoblasts were injected subcutaneously together with matrigel and growth factors in the flanks of nude mice. The inclusion of either bFGF or HGF increased the vascularization of the gels. Gels supplemented with bFGF showed myogenesis accompanied by massive mesenchymal cell recruitment and poor organization of the fascicles. Samples containing HGF showed delayed differentiation with respect to controls or bFGF, with increased myoblast proliferation and a significantly higher numbers of cells in myotubes at later time points. HGF samples showed limited mesenchymal cell infiltration and relatively good organization of fascicles. The use of both bFGF and HGF together showed increased numbers of nuclei in myotubes, but with bFGF-mediated fibroblast recruitment dominating. These studies suggest that an appropriate combination of basement membrane components and growth factors could represent a possible approach to enhance survival dispersion, proliferation, and differentiation of myogenic cells during muscle regeneration and/or myoblast transplantation. This model will help develop cell therapy of muscle diseases and open the future to gene therapy approaches.     

Differential expression of hepatocyte growth factor in liver, kidney, lung, and spleen following burn in rats

Hepatocyte growth factor (HGF) plays a role as an organotropic factor for regeneration of injured organs. HGF is synthesized as an inactive single-chain precursor which is then converted to a biologically active heterodimeric form by proteolytic processing. Burn is the insult that results in hypovolemia which causes systemic organ injury. In this study, we investigated the induction and activation of HGF in various rat organs following burn trauma. Tissue HGF content determined as the total amount of the single-chain and heterodimeric form increased significantly in liver, lung, spleen, and kidney 12 h after burn. Molecular analysis revealed that HGF in these four organs of control rats was the single-chain precursor. In the burned rats, HGF was the single-chain form in the liver and lung, whereas heterodimeric HGF was detected in the spleen and kidney. Tissue protein content, an index of tissue injury, decreased significantly in the spleen and kidney, indicating that tissue damage was severe in these two organs. These results suggest that burn induces the production of HGF in various organs, and that the induced HGF is activated according to the severity of tissue damage caused by burn.