The effect of growth factors on the cytotoxicity of sulphated polysaccharides

Blockage of undesirable endocytosis of recombinant human growth/differentiation factor-5 in Chinese hamster ovary cell cultures requires heparin analogs with specific chain lengths

Cell surface heparan sulfate proteoglycan (HSPG)-mediated endocytosis lowers the yield of recombinant human bone morphogenetic proteins (rhBMPs), such as rhBMP-2 and rhBMP-4, from Chinese hamster ovary (CHO) cell cultures. Exogenous recombinant human growth/differentiation factor-5 (rhGDF-5), a member of the BMP family, bound to cell surface HSPGs and was actively internalized into CHO cells. Knockdown of heparan sulfate (HS) synthesis enzymes in CHO cells revealed that the chain length and N-sulfation of HS affected the binding of rhGDF-5 to HSPGs and subsequent rhGDF-5 internalization. To increase product yield by minimizing rhGDF-5 internalization in recombinant CHO (rCHO) cell cultures, heparin, and dextran sulfate (DS) of various polysaccharide chain lengths, which are structural analogs of HS, were examined for blockage of rhGDF-5 internalization. Heparin fragments of four monosaccharides (MW of 1.2 kDa) and DS (MW of 15 kDa) did not inhibit rhGDF-5 internalization whereas unfractionated heparin and DS of 200 kDa could significantly inhibit it. Compared to the control cultures, supplementation with unfractionated heparin or DS of 200 kDa at 1 g L^-1 resulted in more than a 10-fold increase in the maximum rhGDF-5 concentration. Taken together, the supplementation of structural HS analogs improved rhGDF-5 production in rCHO cell cultures by inhibiting rhGDF-5 internalization. GRAPHICAL ABSTRACT AND LAY SUMMARY: Cell surface heparan sulfate proteoglycan (HSPG)-mediated endocytosis lowers the yield of rhGDF-5 from CHO cell cultures. In this study, the authors found that the length and N-sulfation of HS chain determine the binding of rhGDF-5 to HSPGs and subsequent rhGDF-5 internalization. Based on this finding, the authors successfully used heparin analogs with specific chain lengths to enhance the rhGDF-5 yield by blocking rhGDF-5 internalization.

Immunostimulating and Antimetastatic Effects of Polysaccharides Purified from Ginseng Berry

Ginseng root has been used in traditional oriental medicine for the enhancement of immune system function. The immunostimulatory effects of ginseng berry polysaccharides, however, remain unclear. Effects of polysaccharides from ginseng berry on the activation of natural killer (NK) cells and inhibition of tumors are reported. A crude polysaccharide was isolated from ginseng berry as a ginseng berry polysaccharide portion (GBPP) and was further fractionated using gel filtration chromatography to obtain the three polysaccharide fractions GBPP-I, -II and -III. GBPP-I consisted of mainly galactose (46.9%) and arabinose (27.5%). GBPP-I showed a high dose-dependent anticomplementary activity. Stimulation of murine peritoneal macrophages by GBPP-I showed the greatest enhancement of interleukin (IL)-6 and IL-12 and tumor necrosis factor (TNF)- α production. In addition, an ex vivo assay of natural killer (NK) cell activity showed that oral ( p.o.) administration of GBPP-I significantly increased NK cell cytotoxicity in YAC-1 tumor cells and production of granzyme B. Prophylactic intravenous ( i.v.) and p.o. administration of GBPP-I significantly and dose-dependently inhibited lung metastatic activity in B16BL6 melanoma cells. Depletion of NK cells after injection of rabbit anti-asialo GM1 partially abolished the inhibitory effect of GBPP-I on lung metastasis, indicating that NK cells play an important role in anticancer effects. GBPP-I exerts a strong immune-enhancing activity and can prevent cancer metastasis through activation of NK cells and other immune-related cells.

Synthesis of novel celluloses derivatives and investigation of their mitogenic activity in the presence and absence of FGF2

Novel cellulose sulfates (CS) with a controlled degree of sulfation (DS(S)) were synthesized through acetosulfation as well as direct sulfation. CS containing carboxyl (CO) or carboxymethyl (CM) groups were prepared by TEMPO oxidation or by carboxymethylation with chloroacetic acid. The derivatization was characterized by nuclear magnetic resonance and Raman spectroscopy. The derivatives were investigated regarding their cytotoxicity and mitogenic activity by modulation of 3T3 fibroblast proliferation with or without exogenous FGF2. All derivatives were non-toxic for 3T3 cells. CS strongly promoted FGF2-induced proliferation, which was positively related to overall DS(S). In the absence of FGF2, minute quantities of CS with intermediate degrees of sulfation exerted stronger mitogenic effects than heparin. No significant promoting effects of CO and CM on cell proliferation were found, though the structure of CO shows similarities to heparin.

Synthesis of sulfated colominic acids and their interaction with fibroblast growth factors

Colominic acid, an alpha (2-->8)-linked poly(sialic acid), was sulfated and characterized by NMR spectroscopy. During sulfation, the secondary hydroxyl group at C-4 had almost the same reactivity as the primary hydroxyl group at C-9, while the secondary hydroxyl group at C-7 was hardly substituted. Analysis by molecular modeling suggested that the lack of substitution at C-7 was due to a steric hindrance. A mobility shift assay indicated that FGF-2 bound to the sulfated colominic acid. Synthetic sulfated colominic acid potentiated the mitogenic activity of FGFs for fibroblasts in the same manner as heparin. Sulfated colominic acid with a low degree of sulfation was able to potentiate FGF activity. Regardless of the degree of sulfation, sulfated colominic acid-induced cytotoxicity was not observed. It was suggested that the carboxyl groups in sulfated colominic acid cooperate with the sulfate groups to reinforce the interaction with FGFs and to reduce the cytotoxicity of sulfated colominic acids.

Effects of chondroitin sulfate on colitis induced by dextran sulfate sodium in rats

Chondroitin sulfate (CS) is currently marketed as a therapeutic drug for neurodynia, lumbago and arthrodynia. Recently, many clinical studies have demonstrated the therapeutic effects of orally administered CS against diseases with inflammation. Furthermore, these reports suggest CS plays an important role in the protection of the base of ulcers and has anti-inflammatory activity. We investigated the effects of CS against dextran sulfate sodium (DSS)-induced rat colitis. Rats were given 3% DSS solution for 10 days ad libitum. CS and 5-aminosalicylic acid (5-ASA) were orally administered daily. The doses of the CS groups were 20 or 100 mg/kg and that for the 5-ASA group was 100 mg/kg. Evaluations were made of bloody stools, areas of erosion and hematological data. CS improved the symptoms of bloody stools, erosion and increase of white blood cells. Especially, CS (100 mg/kg) group showed markedly more improvement than the 5-ASA group. We think that the major mechanism of the therapeutic effects of CS are the prevention of tissue damage by the protection of digestive mucosa and anti-inflammatory effects. Therefore, CS may have therapeutic value for alimentary tract diseases such as inflammatory bowel disease or ulcer.