Repeated enemas with hepatocyte growth factor selectively stimulate epithelial cell proliferation of injured mucosa in rats with experimental colitis

A review on the safety of growth factors commonly used in cultivated meat production

Growth factors are commonly added to cell culture media in cellular agriculture to mimic the endogenous process of proliferation and differentiation of cells. Many of these growth factors are endogenous to humans and known to be present in the edible tissues and milk of food animals. However, there is little or no information on the use of growth factors intentionally added in food production before the advent of cultivated meat. Ten commonly used growth factors have been reviewed to include information on their mode of action, bioavailability, occurrence in food and food animals, endogenous levels in humans, as well as exposure and toxicological information drawn from relevant animal studies and human clinical trials with a focus on oral exposure. In addition, a comparison of homology of growth factors was done to compare the sequence homology of growth factors from humans and domestic animal species commonly consumed as food, such as bovine, porcine, and poultry. This information has been gathered as the starting point to determine the safety of use of growth factors in cultivated meat meant for human consumption. The change in levels of growth factors measured in human milk and bovine milk after pasteurization and high-temperature treatment is discussed to give an indication of how commercial food processing can affect the levels of growth factors in food. The concept of substantial equivalence is also discussed together with a conservative exposure estimation. More work on how to integrate in silico assessments into the routine safety assessment of growth factors is needed.

Drug cytotoxicity screening using human intestinal organoids propagated with extensive cost-reduction strategies

Organoids are regarded as physiologically relevant cell models and useful for compound screening for drug development; however, their applications are currently limited because of the high cost of their culture. We previously succeeded in reducing the cost of human intestinal organoid culture using conditioned medium (CM) of L cells co-expressing Wnt3a, R-spondin1, and Noggin. Here, we further reduced the cost by replacing recombinant hepatocyte growth factor with CM. Moreover, we showed that embedding organoids in collagen gel, a more inexpensive matrix than Matrigel, maintains organoid proliferation and marker gene expression similarly when using Matrigel. The combination of these replacements also enabled the organoid-oriented monolayer cell culture. Furthermore, screening thousands of compounds using organoids expanded with the refined method identified several compounds with more selective cytotoxicity against organoid-derived cells than Caco-2 cells. The mechanism of action of one of these compounds, YC-1, was further elucidated. We showed that YC-1 induces apoptosis through the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway, the mechanism of which was distinct from cell death caused by other hit compounds. Our cost-cutting methodology enables large-scale intestinal organoid culture and subsequent compound screening, which could expand the application of intestinal organoids in various research fields.

The preventive effect of recombinant human hepatocyte growth factor for hepatic steatosis in a rat model of short bowel syndrome

PURPOSE

Short bowel syndrome (SBS) patients require total parenteral nutrition (TPN) following massive small bowel resection (SBR), which may cause intestinal failure-associated liver disease (IFALD), a life-threatening complication. Hepatocyte growth factor (HGF) acts as a potent hepatocyte mitogen with anti inflammatory and antioxidant actions. The present study evaluated the effect of recombinant human HGF (rh-HGF) on SBR and subsequent IFALD using a parentally fed rat model of SBS.

METHODS

Rats underwent jugular vein catheterization for continuous TPN and 90% SBR. They were divided into 2 groups: TPN alone (SBS/TPN group: n = 7) or TPN plus the intravenous administration of rh-HGF (0.3 mg/kg/day) (SBS/TPN+HGF group: n = 7). On day 7, their tissues and stool were harvested to evaluate the effects of HGF.

RESULTS

Regarding the histological findings, based on the nonalcoholic fatty liver disease (NAFLD) activity score, the SBS/TPN+HGF group showed significantly less hepatic steatosis and inflammatory cell infiltration than the SBS/TPN group (NAFLD activity score, 4.00 ± 1.83 vs. 1.00 ± 0.82; p < 0.01). The SBS/TPN+HGF group showed a higher expression of Farnesoid X receptor in the liver and lower expression of Toll-like receptor 4 in the ileum than the SBS/TPN group. Regarding the composition of the bacterial gut microbiota, Actinobacteria, Bacteroidetes and Proteobacteria were decreased in the SBS/TPN+HGF group compared with the SBS/TPN group.

CONCLUSION

In our SBS with TPN rat model, rh-HGF administration had a preventive effect against hepatic steatosis and dysbiosis. rh-HGF may therefore be a potentially effective therapeutic agent for SBS and subsequent IFALD.

TYPE OF STUDY

Experimental research.

The protective effects of hepatocyte growth factor on the intestinal mucosal atrophy induced by total parenteral nutrition in a rat model

PURPOSE

Total parental nutrition (TPN) causes gastrointestinal mucosal atrophy. The present study investigated the effects of hepatocyte growth factor (HGF) on the intestinal mucosal atrophy induced by TPN.

METHODS

Rats underwent jugular vein catheterization and were divided into four groups: oral feeding (OF), TPN alone (TPN), TPN plus low-dose HGF (0.3 mg/kg/day; TPNLH), and TPN plus high-dose HGF (1.0 mg/kg/day; TPNHH). On day 7, rats were euthanized, and the small intestine was harvested and evaluated histologically. The expression of c-MET, a receptor of HGF, and nutrition transporter protein were evaluated using quantitative polymerase chain reaction.

RESULTS

The jejunal villus height (VH) and absorptive mucosal surface area in the TPNHH group were significantly higher than in the TPN group (p < 0.05). The VH in the ileum showed the same trend only in the TPNHH group, albeit without statistical significance. The crypt cell proliferation rate (CCPR) of the jejunum in both HGF-treated groups was significantly higher than in the TPN group (p < 0.01). The expression of c-MET and transporter protein in all TPN-treated groups was decreased compared with that in the OF group.

CONCLUSION

HGF attenuated TPN-associated intestinal mucosal atrophy by increasing the villus height, which was associated with an increase in CCPR.

The administration of hepatocyte growth factor prevents total parenteral nutrition-induced hepatocellular injury in a rat model

PURPOSE

Total parenteral nutrition (TPN) sometimes induces parenteral nutrition-associated liver disease (PNALD). Hepatocyte growth factor (HGF) acts as a potent hepatocyte mitogen anti-inflammatory and antioxidant actions. We aimed to evaluate the effect of HGF on PNALD in a rat model of TPN.

METHODS

A catheter was placed in the right jugular vein for 7-day continuous TPN. All rats were divided into three groups: TPN alone (TPN group), TPN plus intravenous HGF at 0.3 mg/kg/day [TPN + HGF (low) group], and TPN plus HGF at 1.0 mg/kg/day [TPN + HGF (high) group]. On day 7, livers were harvested and the histology, inflammatory cytokines and apoptosis were evaluated.

RESULTS

Histologically, lipid droplets were apparent in the TPN group, but decreased in the TPN + HGF (low) and TPN + HGF (high) groups. The histological nonalcoholic fatty liver disease activity scores in the TPN + HGF (low) and TPN + HGF (high) groups were significantly lower than that in the TPN group (p < 0.01). There were no significant differences in the inflammatory cytokine levels of the three groups. The caspase-9 expression levels in the TPN + HGF (low) and TPN + HGF (high) groups were significantly decreased in comparison to that in the control group (p < 0.05).

CONCLUSION

The intravenous administration of HGF attenuated hepatic steatosis induced by 7-day TPN dose dependently.

Hepatocyte Growth Factor and MET Support Mouse Enteric Nervous System Development, the Peristaltic Response, and Intestinal Epithelial Proliferation in Response to Injury

Factors providing trophic support to diverse enteric neuron subtypes remain poorly understood. We tested the hypothesis that hepatocyte growth factor (HGF) and the HGF receptor MET might support some types of enteric neurons. HGF and MET are expressed in fetal and adult enteric nervous system. In vitro, HGF increased enteric neuron differentiation and neurite length, but only if vanishingly small amounts (1 pg/ml) of glial cell line-derived neurotrophic factor were included in culture media. HGF effects were blocked by phosphatidylinositol-3 kinase inhibitor and by MET-blocking antibody. Both of these inhibitors and MEK inhibition reduced neurite length. In adult mice, MET was restricted to a subset of calcitonin gene-related peptide-immunoreactive (IR) myenteric plexus neurons thought to be intrinsic primary afferent neurons (IPANs). Conditional MET kinase domain inactivation (Met(fl/fl); Wnt1Cre+) caused a dramatic loss of myenteric plexus MET-IR neurites and 1-1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyamine perchlorate (DiI) labeling suggested reduced MET-IR neurite length. In vitro, Met(fl/fl); Wnt1Cre+ mouse bowel had markedly reduced peristalsis in response to mucosal deformation, but normal response to radial muscle stretch. However, whole-bowel transit, small-bowel transit, and colonic-bead expulsion were normal in Met(fl/fl); Wnt1Cre+ mice. Finally, Met(fl/fl); Wnt1Cre+ mice had more bowel injury and reduced epithelial cell proliferation compared with WT animals after dextran sodium sulfate treatment. These results suggest that HGF/MET signaling is important for development and function of a subset IPANs and that these cells regulate intestinal motility and epithelial cell proliferation in response to bowel injury.

SIGNIFICANCE STATEMENT

The enteric nervous system has many neuronal subtypes that coordinate and control intestinal activity. Trophic factors that support these neuron types and enhance neurite growth after fetal development are not well understood. We show that a subset of adult calcitonin gene-related peptide (CGRP)-expressing myenteric neurons produce MET, the receptor for hepatocyte growth factor, and that loss of MET activity affects peristalsis in response to mucosal stroking, reduces MET-immunoreactive neurites, and increases susceptibility to dextran sodium sulfate-induced bowel injury. These observations may be relevant for understanding and treating intestinal motility disorders and also suggest that enhancing the activity of MET-expressing CGRP neurons might be a useful strategy to reduce bowel inflammation.

HGF Gene Modification in Mesenchymal Stem Cells Reduces Radiation-Induced Intestinal Injury by Modulating Immunity

Background

Effective therapeutic strategies to address intestinal complications after radiation exposure are currently lacking. Mesenchymal stem cells (MSCs), which display the ability to repair the injured intestine, have been considered as delivery vehicles for repair genes. In this study, we evaluated the therapeutic effect of hepatocyte growth factor (HGF)-gene-modified MSCs on radiation-induced intestinal injury (RIII).

Methods

Female 6- to 8-week-old mice were radiated locally at the abdomen with a single 13-Gy dose of radiation and then treated with saline control, Ad-HGF or Ad-Null-modified MSCs therapy. The transient engraftment of human MSCs was detected via real-time PCR and immunostaining. The therapeutic effects of non- and HGF-modified MSCs were evaluated via FACS to determine the lymphocyte immunophenotypes; via ELISA to measure cytokine expression; via immunostaining to determine tight junction protein expression; via PCNA staining to examine intestinal epithelial cell proliferation; and via TUNEL staining to detect intestinal epithelial cell apoptosis.

Results

The histopathological recovery of the radiation-injured intestine was significantly enhanced following non- or HGF-modified MSCs treatment. Importantly, the radiation-induced immunophenotypic disorders of the mesenteric lymph nodes and Peyer’s patches were attenuated in both MSCs-treated groups. Treatment with HGF-modified MSCs reduced the expression and secretion of inflammatory cytokines, including tumor necrosis factor alpha (TNF-α) and interferon-gamma (IFN-γ), increased the expression of the anti-inflammatory cytokine IL-10 and the tight junction protein ZO-1, and promoted the proliferation and reduced the apoptosis of intestinal epithelial cells.

Conclusions

Treatment of RIII with HGF-gene-modified MSCs reduces local inflammation and promotes the recovery of small intestinal histopathology in a mouse model. These findings might provide an effective therapeutic strategy for RIII.

Vasopressin regulation of epithelial colonic proliferation and permeability is mediated by pericryptal platelet-derived growth factor A

Arginine vasopressin (AVP) has trophic effects on the rat distal colon, increasing the growth of pericryptal myofibroblasts and reducing the colonic crypt wall permeability. This study aimed to reproduce in vitro the effects of AVP observed in vivo using cultures of human CCD-18Co myofibroblasts and T84 colonic epithelial cells. Proliferation of myofibroblasts was quantified by bromodeoxyuridine incorporation; the expression of platelet-derived growth factor A (PDGFA), platelet-derived growth factor B, epidermal growth factor, transforming growth factor-β and vascular endothelial growth factor was measured by PCR and the expression of epithelial junction proteins by Western blot. Arginine vasopressin stimulated myofibroblast proliferation and the expression of PDGFA without affecting the expression of platelet-derived growth factor B, epidermal growth factor, transforming growth factor-β or vascular endothelial growth factor. These effects were prevented when AVP receptor inhibitors were present in the medium. Pre-incubation of CCD-18Co cells with anti-PDGF antibody or with an inhibitor of the PDGF receptor abolished the effects of AVP. When colonocytes were incubated with medium obtained from myofibroblasts incubated with AVP, both cell proliferation and the expression of epithelial junction proteins increased; however, direct incubation of colonocytes with AVP did not modify these variables. These results demonstrate that AVP stimulates myofibroblast proliferation and induces PDGFA secretion, implying that PDGFA mediates local myofibroblast proliferation by an autocrine feedback loop and regulates epithelial proliferation and permeability by a paracrine mechanism.

Intramuscular injection of adenoviral hepatocyte growth factor at a distal site ameliorates dextran sodium sulfate-induced colitis in mice

Inflammatory bowel disease (IBD) severely affects the quality of life of patients. At present, there is no clinical solution for this condition; therefore, there is a need for innovative therapies for IBD. Hepatocyte growth factor (HGF) exerts various biological activities in various organs. However, a clinically applicable and effective HGF-based therapy for IBD has yet to be developed. In this study, we examined the therapeutic effect of injecting an adenoviral vector encoding the human HGF gene (Ad.HGF) into the hindlimbs of mice with dextran sodium sulfate (DSS)-induced colitis. Plasma levels of circulating human HGF (hHGF) were measured in injected mice. The results showed that weight loss and colon shortening were significantly lower in Ad.HGF-infected mice as compared to control (Ad.LacZ-infected) colitic mice. Additionally, inflammation and crypt scores were significantly reduced in the entire length of the colon, particularly in the distal section. This therapeutic effect was associated with increased cell proliferation and an antiapoptotic effect, as well as a reduction in the number of CD4+ cells and a decreased CD4/CD8 ratio. The levels of inflammatory, as well as Th1 and Th2 cytokines were higher in Ad.HGF-infected mice as compared to the control colitic mice. Thus, systemically circulating hHGF protein, produced by an adenovirally transduced hHGF gene introduced at distal sites in the limbs, significantly ameliorated DSS-induced colitis by promoting cell proliferation (i.e., regeneration), preventing apoptosis, and immunomodulation. Owing to its clinical feasibility and potent therapeutic effects, this method may be developed into a clinical therapy for treating IBD.

Amniotic fluid-borne hepatocyte growth factor protects rat pups against experimental necrotizing enterocolitis

Fetal swallowing of amniotic fluid, which contains numerous cytokines and growth factors, plays a key role in gut mucosal development. Preterm birth interrupts this exposure to amniotic fluid-borne growth factors, possibly contributing to the increased risk of necrotizing enterocolitis (NEC) in premature infants. We hypothesized that supplementation of formula feeds with amniotic fluid can provide amniotic fluid-borne growth factors and prevent experimental NEC in rat pups. We compared NEC-like injury in rat pups fed with infant formula vs. formula supplemented either with 30% amniotic fluid or recombinant hepatocyte growth factor (HGF). Cytokines/growth factors in amniotic fluid were measured by immunoassays. Amniotic fluid and HGF effects on enterocyte migration, proliferation, and survival were measured in cultured IEC6 intestinal epithelial cells. Finally, we used an antibody array to investigate receptor tyrosine kinase (RTK) activation and immunoblots to measure phosphoinositide 3-kinase (PI3K) signaling. Amniotic fluid supplementation in oral feeds protected rat pups against NEC-like injury. HGF was the most abundant growth factor in rat amniotic fluid in our panel of analytes. Amniotic fluid increased cell migration, proliferation, and cell survival in vitro. These effects were reproduced by HGF and blocked by anti-HGF antibody or a PI3K inhibitor. HGF transactivated several RTKs in IEC6 cells, indicating that its effects extended to multiple signaling pathways. Finally, similar to amniotic fluid, recombinant HGF also reduced the frequency and severity of NEC-like injury in rat pups. Amniotic fluid supplementation protects rat pups against experimental NEC, which is mediated, at least in part, by HGF.