Mucin synthesis and secretion by cultured tracheal cells: effects of collagen gel substratum thickness

Summary We previously demonstrated that human tracheobronchial epithelial (TBE) cells synthesize mucin and form mucous granules in culture when they are maintained on a collagen gel (CG) substratum, but not on a plastic tissue culture surface or a thin collagen-coated surface (Wu et al., Am. J. Respir. Cell Mol. Biol., 3:467–478; 1990). This observation led us to examine the effects of CG thickness on cell growth and differentiation in primary human/monkey TBE cell cultures. Using the same CG preparation, culture dishes with different thicknesses of CG substratum were prepared. In general, equivalent degrees of cell attachment and proliferation were observed in all cultures maintained on a collagen gel, independent of the thicknesses of CG substratum. However, a greater degree of mucin synthesis and secretion by the cells was observed as the thickness of the CG substratum was increased. Cultures maintained on a thick collagen gel (1 mm) exhibited greater apical membrane complexity, more pseudostratification, and more mucous granules than did cultures maintained on a thin CG substratum. The optimal culture surface for airway mucous cell differentiation contains more than 1-mm thickness of collagen gel substratum.     

THREE-DIMENSIONAL STRUCTURE OF EXTRACELLULAR MATRIX REVERSIBLY REGULATES MORPHOLOGY,PROLIFERATION AND COLLAGEN METABOLISM OF PERISINUSOIDAL STELLATE CELLS (VITAMIN A-STORING CELLS)

The three-dimensional structure of the extracellular substratum was found to regulate reversibly the morphology, proliferation and collagen synthesis of perisinusoidal stellate cells (lipocytes, i.e. fat-storing ‘Ito’ cells). On non-coated polystyrene and type I collagen-coated culture dishes, the cells spread well and extended their cellular processes. On the surface of type I collagen gels, the cells gathered and formed a mesh-like structure. However, in type I collagen gel where the cells were surrounded by type I collagen three-dimensionally, the cells extended their fine cellular processes and resembled the star-shaped stellate cells seenin vivo. The cell proliferation was more prominent in culture dishes coated with type I collagen or in polystyrene culture dishes than on or in type I collagen gels. The collagen synthesis was affected in the same manner. These data indicate that the nature and the three-dimensional structure of the extracellular matrix (ECM) can regulate morphology, proliferation and functions of the perisinusoidal stellate cells. In order to examine the reversibility of these regulations, we liberated cultured cells with trypsin or with purified bacterial collagenase and re-seeded them onto or into each substratum. The cells changed their shape, rate of proliferation and collagen synthesis according to each new substratum. These results indicate that the three-dimensional structure of ECM reversibly regulates the morphology, proliferation rate and functions of the perisinusoidal stellate cells.     

The different effects of type I and IV collagens on the survival and proliferation of cultured BSC-1 cells

The effects of type I and IV collagens on the survival and proliferation of cells were investigated to clarify a possible involvement of the substratum in the regulation of cell function. BSC-1 cells attached, spread and sustained their viability in the absence of calf serum on culture dishes coated with type IV collagen, but were unable to spread and survive on untreated culture dishes. The effects of adding type IV collagen in solution were similar to those of type IV coating. The fraction of the solution of type IV collagen with molecular mass of more than 100 kDa enhanced spreading and survival of cells, but the fraction of less than 100 kDa did not. Type I collagen did not support cell viability in the absence of calf serum. Moreover, coating of culture dishes with type I collagen, but not with type IV collagen, inhibited DNA synthesis and cell proliferation in the presence of calf serum. The cells grown on type I collagen were long, thin and spindle-shaped, and their stress fibers were not well developed, but the cells grown on type IV collagen, as well as those grown on untreated culture dishes, were polygonal in shape with well-developed stress fibers. These results indicate that the interactions of BSC-1 cells with the substratum, when it is derived from type I and IV collagens, differentially modulate the survival and proliferation of BSC-1 cells.     

The synthesis of subendothelial matrix by bovine aortic endothelial cells in culture

Bovine aortic endothelial cells cultured on collagenous or plastic substrata continuously synthesize and deposit a subendothelial matrix, independently of whether the cells are in the logarithmic or the stationary phase of growth. This subendothelial matrix contains fibrillar and amorphous elements comparable with those observed in the subendothelium in vivo. Deposition of subendothelial matrix on a collagen gel substratum both started earlier and progressed at approximately double the rate than that on denatured collagen. The relative composition of the subendothelial matrix was assessed by sequential incubation with trypsin, elastase and collagenase (Jones et al., 1979). The subendothelial matrix deposited on collagen gels by early confluent cultures and late post-confluent cultures differed in their enzyme sensitivity. These age-related changes in the enzyme sensitivity of the subendothelial matrix were characteristic for each cloned cell population examined. Comparable variations in the composition of the subendothelial matrix were not observed when the cells were cultured on plastic or gelatin-coated dishes; the subendothelial matrix deposited on these two substrata contained considerably more trypsin-sensitive material and less elastase and collagenase-sensitive material than the matrix deposited on native collagen gels. Age-related changes in the enzyme sensitivity of the subendothelial matrix deposited on collagen gels was found to be a function of the time elapsed since confluence and it was not related to the time elapsed since plating or to the number of cells present.     

Influence of collagen gel substratum on response to low-density lipoprotein by cultured human skin fibroblasts

The effect of low-density lipoprotein (LDL) on accumulation of glycosaminoglycans (GAG) was compared in cultures of human skin fibroblasts on a conventional plastic substratum and in a native type I collagen gel. The 24-h incorporation of [3H]glucosamine and Na2(35)SO4 into GAG secreted into the medium or associated with the substratum and cell surface (SCA) was measured in cells at subconfluent densities. When cells were grown on plastic, 13-25% of the labeled GAG was in the SCA pool. Cells cultured within a collagen gel matrix incorporated three times more [3H]glucosamine and up to five times more [35S]sulfate into this pool. The addition of LDL (300 micrograms protein/mL) to the medium increased the level of total GAG incorporation of [3H]glucosamine by 40-50% and of [35S]sulfate by 15-20% on both substrata. For cells on plastic the relative increase in the medium and SCA pool was similar, whereas for cells in collagen gel the response to LDL was twice as great in the SCA pool as in the medium. The distribution of GAG types was unaffected by LDL; hyaluronic acid remained the principal GAG in the media pools of both substrata, heparan sulfate remained the main SCA GAG in cultures on plastic, and dermatan sulfate remained the dominant GAG in the SCA pool of collagen gel cultures. LDL degradation was measured at intervals up to 48 h after the addition of 125I-labeled LDL. The rate of accumulation of degraded LDL products was lower in collagen gel cultures, but the final levels achieved were the same in the two substrata. Concentrations of total cell cholesterol were similar, although the increases in free cholesterol induced by LDL were 26% greater in cells within collagen gel than in those on plastic. We conclude that fibroblasts grown within a collagen gel, as compared with those on a plastic substratum, (i) accumulate more GAG that remain attached to the substratum and cell surface; (ii) respond to LDL with a similar degree of increase in GAG accumulation, but more of the increase is found in the substratum and cell surface compartment; and (iii) accumulate more intracellular free cholesterol in response to LDL.     

The matrix form of collagen and basal microporosity influence basal lamina deposition and laminin synthesis/secretion by stratified human keratinocytes in vitro

Summary The ability of the collagen matrix form to support the formation of a basal lamina by cultured normal human epidermal keratinocytes (NHEK) was determined using transmission electron microscopy. The collagen matrix forms tested in this study were a) a dry type I collagen film and b) a type I collagen gel. NHEK were grown for 14 days on the following five different substrates: plain plastic culture dishes without the addition of collagen (PP); plain plastic culture dishes overlaid with a dry, aldehyde-crosslinked type I collagen film (DCF-P); plain plastic culture dishes overlaid with an aldehyde-crosslinked type I collagen gel (GEL-P); Millipore Millicell CM microporous membranes overlaid with a dry, aldehyde-crosslinked type I collagen film (DCF-CM); and Millipore Millicell CM microporous membranes overlaid with an aldehyde-crosslinked type I collagen gel (GEL-CM). NHEK maintained for 2 wk on PP and DCF-P were unable to secrete a basal lamina. NHEK grown for 2 wk on the GEL-P and GEL-CM substrates, however, secreted a contiguous basal lamina at the GEL-NHEK interface. To determine if the appearance of this basal lamina correlated with laminin synthesis, laminin was immunoprecipitated from cellular extracts, as well as media from the apical and basal chambers. NHEK grown on the GEL-P substrate synthesized more laminin than did NHEK grown on the other four alternative substrates. In addition, NHEK grown on GEL-CM were able to direct more laminin to the basal compartment than NHEK grown on DCF-CM substrates. Taken together, the data indicate that the matrix form of collagen can influence basal lamina deposition, laminin synthesis, and laminin trafficking in NHEK.     

Differential Effects of TGF-β1 on Hyaluronan Synthesis by Fetal and Adult Skin Fibroblasts: Implications for Cell Migration and Wound Healing

Fetal wound healing differs from its adult counterpart in that it is regenerative and occurs without scarring. The matrix macromolecule hyaluronan (HA) and various cytokines, including members of the TGF-β family, have been implicated in the control of scarring. We have previously reported that adult and fetal fibroblasts differ with respect to the effect of cell density on HA synthesis when cultured on plastic tissue culture dishes. Data regarding the effects of substratum and TGF-β1 on HA synthesis by these cells are presented in this communication. Our results indicate that HA synthesis by both fetal and adult fibroblasts is (a) up-regulated by culture on a collagen substratum and (b) differentially regulated by TGF-β1 in a manner which is dependent upon both substratum and cell density. TGF-β1 stimulated HA synthesis by confluent fetal fibroblasts growing on a plastic substratum, but inhibited HA synthesis on a collagen substratum; these data underscore the important role of the substratum in determining the precise effect of TGF-β1 on cell behavior. Related studies indicated that the migration of fetal and adult fibroblasts into the collagen substrata was modulated by TGF-β1 in a manner identical to its effect on HA synthesis. These observations are discussed in terms of the contribution of distinct fibroblast subpopulations to wound healing and the manner in which this is regulated by matrix and cytokines.     

Cell-to-substratum adhesion and guidance of axonal elongation

The behavior of axonal growth cones on surfaces with patterned variations in substratum was observed. Cells from sensory ganglia of 8-day-old chicken embryos were cultured on plastic petri dishes, plastic tissue culture dishes, and polyornithine-coated tissue culture dishes, all of which contained gridlike patterns of palladium (Pd) deposition.The results indicated that growth cones elongated on the Pd-shadowed areas vs areas lacking Pd deposits depending on the relative adhesivity of the growth cones to the substrata. In petri dishes, growth cones stay on the Pd; in tissue culture dishes, they cross from one surface to the other; and in polyornithine-coated dishes, they elongate for great distances on the Pd-free areas. Analyses of time-lapse movies showed that, on Pd-shadowed polyornithine dishes, growth cones often approach the Pd-coated areas and microspikes touch the Pd surface. Yet, the axon tip continues to elongate on the Pd-free polyornithine surface.The conclusion is offered that interactions between microspikes and the substratum adjacent to the growth cone are important determinants of the directions and pathways of axonal elongation.     

Elongation of axons in an agar matrix that does not support cell locomotion

Axons elongate from 8-day embryonic chick spinal ganglion neurons cultured in a soft agar matrix or on a firm agar substratum. Glial cells from the same ganglia are unable to spread or show locomotory behavior (ruffling) in or on the agar, but do spread and show ruffling activity at the agarplastic interface or when replated from agar onto plastic. Axons elongated into or on agar retract much more slowly when treated with colchicine than do similar axons on plastic dishes.     

Cell substratum modulates responses of preosteoblasts to retinoic acid

The aim of this study was to determine the role of ECM components of bone in regulating the differentiation and function of cells of the osteoblast lineage. Rat UMR 201 cells, phenotypically preosteoblast, were plated onto plastic tissue culture dishes or dishes coated with gelled type I collagen or reconstituted basement membrane (matrigel). Acute cell attachment assays showed that cells adhered to substrates in the following order: collagen > matrigel ? plastic. Proliferation rate up to 96 hr were similar on each substrate. However, if cells were treated with 10^?6 M retinoic acid (RA), proliferation rates were reduced compared with control for cells grown on collagen and matrigel but not on plastic. Morphological changes were matrix-specific; in subconfluent cultures, long thin processes were seen with cells grown on collagen and a pattern of interconnecting cell processes formed when cells were plated on matrigel. Striking differences were observed in the constitutive or RA-induced gene expression of cells grown on the different substrates. When cells plated on collagen were treated with RA, induction of mRNA for alkaline phosphatase (ALP) as well as ALP enzyme activity were much less than with cells grown on plastic. In contrast, RA treatment induced osteopontin (OP) mRNA expression more strongly in cells plated on collagen compared with plastic within 24 hr and this was maintained for 72 hr. RA treatment produced a two fold increase of pro-α 1(I) collagen mRNA in cells grown on plastic and matrigel but not in cells grown on collagen. Growth on collagen produced changes in the way UMR 201 cells responded to RA from which they did not fully recover in subsequent 48-hr growth periods on plastic. These results indicate that ECM components regulate the function of and are capable of modulating RA-induced differentiation of preosteoblasts. © 1993 Wiley-Liss, Inc.     

Interactions of extracellular collagen and corneal fibroblasts: Morphologic and biochemical changes of rabbit corneal cells cultured in a collagen matrix

Summary Corneal fibroblasts, also known as keratocytes are surrounded by an extracellular matrix of collagen in vivo. To understand the physiology and pathology of these corneal fibroblasts, it is important to study their interactions with this extracellular matrix. We cultured rabbit corneal fibroblasts on tissue culture plastic dishes or in a hydrated collagen gel and compared the changes in morphology and mitotic activity. Corneal fibroblasts on plastic dishes were flattened and widely spread, whereas those in collagen gel became spindle-shaped with long processes. Examination with an electron microscope revealed that the corneal fibroblasts in collagen gel formed gap junctions with neighboring cells. Gap junctions were hardly ever observed between corneal fibroblasts cultured on plastic dishes. Corneal fibroblasts cultured in a collagen matrix showed much less incorporation of [³H]thymidine than did corneal fibroblasts cultured on plastic, and this incorporation decreased with increasing concentration of collagen. Our present results suggest that the morphologic and biochemical characteristics of corneal fibroblasts cultured in collagen gel are different from those cultured on plastic. This research was supported in part by grants from the Ministry of Education, Science and Culture of Japan, by a grant from Osaka Eye Bank, Osaka, Japan, and by an intramural research fund of Kinki University. Part of this research was presented at the annual meeting of the Japanese Ophthalmological Society (May 1985) at Kyoto, Japan, and at the annual meeting of the Association for Research in Vision and Ophthalmology (May 1987) at Sarasota, FL.     

Proteins excreted by primary human colon carcinoma cells (SW 480) promote spreading and growth of metastatic human colon carcinoma cells (SW 620) in serum-free medium

The growth behavior of the two human colon tumor cell lines (SW 480, primary and SW 620, metastatic), originating from the same patient, was studied in six different serum-free media (SFM) [GF3, Chee's essential medium plus insulin, transferrin and selenium; GF3F, GF3 plus fetuin; GF4, GF3 plus linoleic acid-BSA; GF5, GF4 plus fetuin; GF5E, GF5 plus EGF; GF5T, GF5 plus triiodothyronine]. SW 480 grew in all of the SFM. In contrast, SW 620 grew only in four SFM. The cells did not grow in GF3 and GF4. When grown in SFM, SW 480 attached much more firmly to the dishes than SW 620 as determined by the time required to detach the cells with trypsin-EDTA (SW 480, greater than 20 min and SW 620, less than 5 min). It was speculated that SW 480 cells excrete proteins in SFM which influence attachment and growth of the cells. Growth behavior of SW 480 cells which did not grow in GF3, was studied using GF3 medium and SW 480 substratum dishes. SW 620 cells readily attached to the SW 480 substratum dishes and grew. Furthermore, when SW 620 cells were grown on substratum prepared from serum-supplemented medium incubated in the absence of cells (serum substratum), the cell growth was comparable to the cell growth on SW 480 substratum in GF3. Substratum from SW 480 cells and the serum substratum were compared for their components using SDS-PAGE system. The SW 480 substratum contains many more components than serum substratum. A protein band at 60 kD appears to be common in both SW 480 and serum substrata.     

Magnesium-dependent attachment and neurite outgrowth by PC12 cells on collagen and laminin substrata

We report a study of the substratum and medium requirements for attachment and neurite outgrowth by cells of the pheochromocytoma-derived PC12 line. In attachment medium containing both Ca2+ and Mg2+, more than 50% of cells attached within 1 hr to petri dishes coated with native collagen Types I/III or II, native or denatured collagen Type IV, laminin, wheat germ agglutinin (WGA), or poly-L-lysine; attachment to dishes coated with nerve growth factor (NGF) was only about 20% and attachment to uncoated dishes or to dishes coated with fibronectin or gelatin was almost nil. Neither prior culturing in the presence of NGF nor addition of NGF to the attachment medium significantly affected the extent of attachment to collagen or laminin. With Ca2+ (1 mM) as the sole divalent cation, cells attached normally to WGA, polylysine, and NGF, but failed to attach to collagen or laminin. With Mg2+ (1 mM) as the only divalent cation, attachment to all substrata was about the same as in medium with both Ca2+ and Mg2+. Like the ionic requirements, the kinetics of attachment, insensitivity to protease treatment of the cells, and inhibition by low temperature and sodium azide were similar for PC12 attachment to collagen and laminin, suggesting that a common molecular mechanism may underlie attachment to these substrata. The only significant difference observed was that addition of WGA (30 micrograms/ml) to the attachment medium inhibited attachment to collagen but promoted attachment to laminin. Finally, PC12 cells extended neurites on laminin, on native collagens I/III, II, and IV, and on denatured collagen IV; they did not extend neurites on denatured collagens I/III or II, NGF, or WGA. Neurite outgrowth on collagen and laminin occurred with Mg2+ as the sole divalent cation. These results suggest that the same Mg2+-dependent adhesion mechanism operates at the cell body and at the growth cone.     

Inhibition of cell adhesion by type V collagen.

Human umbilical vein endothelial cells grew well in dishes coated with collagen types I, II, III, or IV. However, the same cells tended to detach themselves from dishes coated with type V collagen, and cell proliferation in these dishes was inhibited. Such anti-adhesive activity was partially retained by heat-denatured type V collagen or by its alpha 1 chain, but not by its alpha 2 chain. Several other cell types did not adhere to the type V collagen substratum even in the presence of 10% serum. The cell types strongly inhibited from adhering by type V collagen included Swiss mouse 3T3 cells and their MSV-transformants, BALB/c 3T3 cells and their methylcholanthrene-transformants, NIH 3T3 cells and their ras-transformants, BHK cells, CHO-9 cells, CHO-K1 cells, and mouse melanoma B16-F10 cells. Using Swiss mouse 3T3, we studied the effects of type V collagen on cell adhesion to fibronectin in serum-free medium. When the culture dishes were coated with a mixture of fibronectin with various concentrations of type V collagen, the adhesion of the cells was inhibited depending on the concentration of type V collagen. The inhibition of cell adhesion by type V collagen was competitively overcome by increased concentrations of fibronectin. The activity that interferes with the effects of fibronectin was retained mainly by the alpha 1 chain of heat-denatured type V collagen.     

Substratum influence on collagen and fibronectin biosynthesis by arterial smooth muscle cells in vitro

Collagen, fibronectin, and nonfibrous protein biosynthesis were examined in cultures of rabbit arterial smooth muscle cells grown on tissue culture plastic precoated either with rabbit plasma fibronectin or bovine serum albumin. Cells seeded into fibronectin-coated wells appeared to reach confluence more quickly than counterparts grown on albumin-coated surfaces. Measurement 3H-thymidine incorporation into DNA by these cultures suggested that this was probably a consequence of more rapid and efficient cell attachment rather than an increased rate of proliferation of smooth muscle cells grown on fibronectin. In preconfluent cultures, the rates of collagen and fibronectin biosynthesis were reduced to 34 and 57%, respectively, on a per-cell basis in cultures grown on fibronectin-coated surfaces compared with cells grown on albumin-coated plasticware. In preconfluent cultures grown on fibronectin-coated surfaces, a greater percentage of the total fibronectin synthesized was incorporated into the cell layer. The distribution of newly synthesized collagen between culture medium and cell layer, however, was not affected by alteration of substratum composition. There was no difference in the rate of synthesis of noncollagen proteins between the two groups of preconfluent cells. In postconfluent cultures the rates of collagen and fibronectin biosynthesis were equivalent in both albumin- and fibronectin-treated cultureware. In preconfluent cultures, analyses of procollagens showed that the overall amounts of both types I and III procollagens were reduced in fibronectin-treated wells, indicating the reduction in collagen synthesis to be general and not type-specific. Although type V procollagen biosynthesis was not detected in either preconfluent group, it was found in postconfluent cultures. The reduction of fibronectin synthesis in cells grown in fibronectin-coated wells was significant as early as 4 hours after plating. Together, these findings suggest that cultured arterial smooth muscle cells are capable of deriving information from their substratum and regulating the biosynthetic rates of extracellular matrix components in response to the immediate needs of the cell.     

Effect of serum,fibronectin, and laminin on adhesion of rabbit intestinal epithelial cells in culture

Rabbit intestinal epithelial cells, obtained after a limited hyaluronidase digestion, were incubated in medium with or without calf serum, on bacteriological plastic dishes. The dishes, either plain or coated with an air-dried type I collagen film, were pretreated with medium alone or with medium containing purified laminin or purified fibronectin. Cells did not attach in significant numbers to untreated bacteriological plastic, even in the presence of serum. Cells did attach to collagen-coated dishes, and were judged viable on the basis of their incorporation of radiolabeled leucine into cell protein. Cell adhesion to the collagen substrate increased in proportion to the concentration of serum in the medium, with maximal attachment at 5% serum or greater. Pretreatment of plain or collagen-coated dishes with increasing amounts of fibronectin enhanced cell adhesion in a concentration-dependent manner. Either serum, or fibronectin-free serum in the medium enhanced cell attachment to substrates pretreated with cither fibronectin or laminin. Thus, intestinal epithelial cells appear to possess surface receptors for both laminin and fibronectin. The evidence further suggests that calf serum may contain factors, other than fibronectin, capable of enhancing intestinal epithelial cell attachment to collagen substrates.     

Effect of the extracellular matrix on plasminogen activator isozyme activities of human mammary epithelial cells in culture.

Multiple molecular forms of plasminogen activator were detected in normal human mammary epithelial cells in culture. Cells derived from (normal) breast mammoplasty specimens and grown on the surface of collagen gels exhibited three major classes of plasminogen activator isozymes (Mr = 100,000 [100K], 75,000 [75K], and 55,000 [55K]). The activity of the 100K and 75K isozymes was greatly reduced when the cells were grown on conventional tissue-culture-grade plastic surfaces. MCF-7, a human mammary carcinoma cell line, exhibited predominantly or exclusively the 55K isozyme, irrespective of the cell growth substratum. The activity of the 55K isozyme was more than twofold higher for MCF-7 cells grown on collagen gels than for cells grown on plastic. Progesterone, diethylstilbestrol, and estrogen stimulated the activity of the 55K isozyme of MCF-7 cells, but only when the cells were grown on a plastic surface. The plasminogen activator activities of the normal human mammary epithelial cells were not stimulated by these hormones, irrespective of the growth substratum. These results show that the expression of plasminogen activator isozymes by human mammary epithelial cells is subject to modulation by the extracellular matrix. Normal and malignant cells may differ in their responsiveness to these effects.     

A comparison of the effects of different substrata on chondrocyte morphology and the synthesis of collagen types IX and X

Summary Embryonic chick sternal chondrocytes were cultured either within three dimensional gels of type I collagen, type II collagen or agar, or as monolayers on plastic dishes coated with air-dried films of these matrix macromolecules. It was observed that cell shape and cell growth varied markedly between the different culture conditions. Flattened monolayers of cells on plastic or films of type I or type II collagen, proliferated more rapidly and reached a higher final cell density per culture than the more rounded cells found in the cultures on agar films or within three-dimensional gels. Biosynthetic studies demonstrated that in addition to the synthesis of type II collagen, all the cultures were producing collagen types IX and X. Chondrocytes cultured on plastic or films of the different matrix macromolecules all showed a similar expression of types IX and X collagen, independent of whether they displayed a flattened or round cell morphology. In contrast, marked variations in the proportions of the minor collagens, particularly type X collagen, were observed when the cells were cultured within three-dimensional gels. The data suggest that direct interaction of the cell surface with matrix constituents displaying a particular spatial array could be an important aspect in the control of type IX and X collagen expression by chondrocytes. The financial support of the Arthritis & Rheumatism Council and the Medical Research Council is gratefully acknowledged.     

Proliferation of oligodendrocytes is stimulated after their adhesion on a matrix made up of a nerve lectin, CSL

It is shown that oligodendrocytes (myelin producing cells in the central nervous system) can adhere to a substratum constituted by an endogenous cerebellar soluble lectin (CSL) adsorbed on plastic Petri dishes. This adhesion induces a rapid and important proliferation of cultured oligodendrocytes.