Cell Response To Different Concentrations Of Growth Sera Biology Essay

Culture of mammalian cells in vitro is indispensable for the survey of mammalian viruses and the class of their reproduction and virulency, every bit good as in cytogenetic, biochemical, and molecular research and for diagnostics1. Generally, Eukaryotic cells are more hard to turn than procaryotic cells due their complex media demands and susceptibleness to contamination.2 Mammalian cells must besides be incubated at an appropriate temperature and gas mixture, of 37EsC and 5 % CO2, for most mammalian cell lines.

Normally, primary cell civilizations have a limited lifetime and after a certain figure of unit of ammunitions of mitosis, known as the Hayflick Limit, cells senesce due to the shortening of telomeres to a critical threshold, which prevents farther division of cells. Established cell lines, on the other manus, can proliferate indefinitely in the right civilization conditions, either as a consequence of self-generated mutant or through calculated alteration. Such cell lines may be derived from carcinoma cells, where the activity of telomerase, the enzyme which prevents consecutive shortening of telomeres, is altered. Cells from the original tissue can be grown and passaged repeatedly to give rise to a comparatively stable cell line. The procedure of passaging, or sub-culturing cells enables an single grow cells in civilization for extended periods of clip, leting their growing response to specific conditions to be assayed.1

Cells are passaged by taking cell monolayers from the surface of the primary civilization vas by trypsinization or by mechanical agencies and the cell suspension is so subdivided into fresh civilizations. Secondary civilizations are monitored for growing and alterations in conditions and may be farther passaged. The clip between passaging cells depends on the growing rate and varies with the cell line. The growing media used contains supplemented factors, frequently en derived from carnal blood, such as fetal calf serum. It is critical to choose the tissue civilization medium suitable for the type of cells to be cultured and type of intervention they are used for. Media are available commercially in liquid signifier or in a powdery signifier, or instead, specific media may be prepared. Contamination is a major issue in the civilization of mammalian cells, and taint about entirely occurs from managing of civilizations, reagents and stuffs, therefore good sterile technique must be maintained. All stuffs that come into contact with civilizations must be unfertile and attention must be taken to maintain the work environment every bit clean. The media of pick may so be supplemented with antibiotic and/or fungicide to forestall growing of contaminants.1, 2

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The aims of this experiment were to transport out the protocols for passaging mammalian two cell lines: HeLa and babe hamster kidney cells ( BHK ) , supervise them by detecting their visual aspect and roll uping samples in order to measure the cells ‘ growing response to different serum concentrations in the civilization medium. The footing of this experiment is the fact that the sum of protein released from each cell upon lysis can be used to cipher the figure of cells in each civilization, and therefore the clip taken for the cells to duplicate.

Materials and Methods

The Experiment was carried out harmonizing to the practical process described in the research lab manual, pages 11-17.Over the class of five yearss, two cell lines, BHK and HeLa, were each cultured in two specific media incorporating different concentrations of Foetal Calf Serum. Each civilization was passaged four times to give a sum of 16 dishes. One civilization of each cell type and serum concentration was analysed over the undermentioned four yearss and samples collected for analysis of protein concentration at a ulterior day of the month. The concentration of each civilization was examined.

For measure 4 ( degree Celsius ) on page 11/12For the finding of cell concentration in the original cell suspensions, the cells were diluted 1/5 in versene i.e. to give a suited cell concentration for numbering, of about 6 ten 105 cells/ml. For measure 2. On page 16, the standard protein was diluted to 0.1-0.9 mg/ml protein with increases of 0.1 mg/ml to give a dilution series in order to obtain a standard curve.

Cells were washed in media +2 % serum, as per measure 8 ; p. 13 of the research lab manual, before re-plating the cells in appropriate medium in order to take the concentrated ( about 16.67 % ) FCS used in measure 3 ( vitamin D ) on page 11 of the research lab manual. This concentration of serum is far higher than the optimum concentration and is merely required in the remotion of primary civilizations from the home base. Excluding this measure may ensue in rapid growing that may be impossible to supervise and early decease of cells due to overcrowding and build-up of toxic metabolic merchandises.

The Standard Cell pellets were washed in Phosphate Buffered Saline as per page 13, measure 8 in the lab manual earlier stop deading to take any staying media and to keep the ionic concentration and therefore the osmolarity of the cell pellets to forestall cell decease after dissolving.


The consequences are presented with hours as the step of clip, since the working in footings of yearss would hold made the consequences less accurate. However, the allocated clip for working in the labs was non the same on each twenty-four hours and the exact clip of harvest home of each sample was non recorded. Therefore the consequences are presented at intervals of 24 hours, even though this is somewhat inaccurate.

The concentration and figure of cells in the undiluted suspension, found utilizing Neubauer numbering chamber, were as follows:

HeLa cell line: 330 cells counted in entire

Concentration of cells = 3.90 ten 105 cells/ml

Number of cells in suspension = 3.90 x 106 cells.

BHK cell line: 175 cells counted in entire

Concentration of cells = 4.38 ten 106 cells/ml

Number of cells in suspension = 4.38 x 107 cells.

The expected figure of HeLa cells was about 8 ten 106, around half the value calculated. The expected figure of BHK cells was about 1-2 ten 107, and the value calculated was about dual the upper bound of the expected figure of cells.

Figure 1 shows that the estimations of per centum coverage of dishes as observed with an upside-down visible radiation microscope. Cells of the same line covered about the same surface per centum after 24 hours of incubation. The BHK cells in GMEM/10 % FCS grew at the greatest rate and had reached the highest per centum confluency by 96 hours after passaging. Judging by the gradient of the computerised line of best tantrum, the HeLa cells in DMEM/10 % FCS grew at about the same rate, though after 24 hours, the per centum coverage was 5 % less, at 20 % . The HeLa cells in DMEM/2 % FCS and BHK cells in GMEM/2 % FCS besides grew at about the same rate as each other, but a slower rate than the cells in 10 % FCS. The BHK cells in GMEM/2 % FCS besides covered a larger per centum than the HeLa cells in DMEM/2 % FCS at all clip points.

Since the Lysis Buffer that was used as a space in the spectrophotometer was contaminated, the first two consequences of the lowest dilutions of serum were negative. Zero was set as the baseline for these values and 0.015 was added to each HeLa reading and 0.035 added to each BHK reading to account for this. Thus, no values were recorded for each of the cell lines in 2 % FCS. The A590 values of the HeLa in DMEM/10 % FCS harvested at 72 and 96 hours were higher than scope of standard graph ( shown in blue ) , so the solution was diluted 1 in 2 and the A590 re-measured. This dilution was accounted for by duplicating the concentration of protein read from the standard curve. The corrected and diluted ( in the instance of BHK 10 % 72 and 96 H ) values were used to cipher the sum of protein released from each cells and the entire cell figure in each infusion.

Table 2: A590 Cell infusions

Cell Line in Media/serum

Length of Incubation ( hours )

Standard Cell Pellets


HeLa DMEM/ 2 % FCS

HeLa DMEM/10 % FCS









BHK: 0.439




( Undiluted ) 1.186

( Diluted 1 in 2 ) 0.439

( Undiluted ) 1.270

( Diluted 1 in 2 ) 0.730

The spectrophotometric check was calibrated with standard protein solution to bring forth a standard curve of protein concentration ( Figure 2, see appendix ) . The concentration of protein in each civilization was estimated from Figure 2.

Table 3: Concentration of protein estimated from Figure 2 ( Appendix ) ( mg/ml )

Cell Line in Media/serum

Length of Incubation ( hours )





HeLa DMEM/ 2 % FCS




HeLa DMEM/10 % FCS














As described above, no values were recorded for each of the cell lines in 2 % FCS. The concentration of protein in the HeLa civilization in DMEM/ 2 % FCS rose steadily between 48 and 72 hours and more quickly between 72 and 96 hours in the brooder. The concentration of protein in the HeLa in DMEM/10 % FCS precisely doubled over the class of the check. There was a big bead in protein concentration after 72 hours of incubation of the BHK civilization in GMEM/2 % FCS, and after 96 hours the concentration had increased to little more than the value at 48 hours. The concentration of protein in the BHK civilization in GMEM/10 % FCS rose really quickly after the first 24 hours, rose at a slower rate until 72 hours and so rose really steeply between 72 and 96 hours.

The Concentration of protein from the standard curve ( Table 3, appendix ) and the Original Volume of the civilization extracts ( Table 4, appendix ) were used to cipher the sum of protein released from each cell ( Table 5 ) , and the entire cell figure per civilization ( Table 7, Appendix and Figure 2 ) . Figure 2 shows the logged values of the cell Numberss. Detailss of computations are included in the appendix.

Table 5: Concentration of protein released from each cell ( mg/ml )

Cell Line in Media/serum

Length of Incubation ( hours )





HeLa DMEM/ 2 % FCS




HeLa DMEM/10 % FCS














The gradient of the tendency line of each information set was used to cipher the T1/2 of each civilization.

Table 6: Cell Doubling Times calculated from Figure 2

Cell Line in Media/serum

Doubling Time ( hours )

HeLa DMEM/ 2 % FCS


HeLa DMEM/10 % FCS






Figure 2 shows that the HeLa civilization in DMEM/ 2 % FCS and the BHK civilization in GMEM/ 10 % FCS had similar gradients and hence similar duplicating times were calculated, though the HeLa civilization had a somewhat lower doubling clip, intending that he cells grew faster. The HeLa civilization in DMEM/ 10 % FCS had a doubling clip of precisely 24 hours, which was expected, since the A590 and concentration of protein in each consecutive infusion was dual the infusion harvested 24 hours prior. The BHK civilization in DMEM/ 2 % FCS had a much higher duplicating clip, since the gradient from Figure 2 is really gradual due to the much lower A590 ( and hence cell figure ) reading at 72 hours, and the fact that the cell figure at 96 was non much higher than the cell figure at 48 hours. Therefore, the overall cell figure increases really small over the class of the experiment. The first 24 hours of growing were non recorded, but this was when growing was fastest, judging by the fact that this is the highest informations point at 48 hours. It must besides be noted that no informations were collected at 24 hours for each cell line in 2 % FCS for grounds stated above, and hence there are merely three clip points for these civilizations. The deductions of this are explored in the treatment subdivision.

The information of the BHK cells in GMEM/2 % FCS does non correlate with the per centum coverage of the plastic home bases ( Figure 1 ) , which increased linearly over the class of the experiment. The last informations point from this cell civilization had the lowest cell figure ( Figure 3 ) , but the 2nd lowest per centum screen after 92 hours. The per centum coverage ( Figure 2 ) of cell civilizations in 10 % FCS correlated more closely with the cell figure ( Figure 1 ) . The per centum coverage of the BHK cells in GMEM/10 % FCS was lowest at all clip points in Figure 1, conversely, the cell figure on Figure 2 is much lower than the figure of cells in the other civilizations at 48 hours and is merely somewhat lower than the cell figure of the other HeLa civilization at 76 hours and around the same at 96 hours.


The original informations collected could non be used, due to taint of stuffs and reagents, including the lysis buffer that was used as a space for the spectrophotometric checks. Although this may hold meant that the A590 reading of the infusions were inaccurate, this should hold been negated by the fact that the space was besides contaminated, although the beginning and type of taint was unknown.

The first informations collected in this experiment was the per centum screen of cells in each of the samples over 96 hours. The BHK civilizations had covered a greater per centum of the surface by the terminal of the experiment. The cells in 10 % FCS grew at a somewhat faster rate. However, these figures may be misdirecting because the BHK cells were longer and dilutant, and therefore may hold appeared to cover more surface are than the smaller HeLa cells. It was besides hard to gauge the per centum coverage, since the cells were non equally distributed over the surface of the dishes in any of the civilizations, with the Centre of the dishes being more feeder than the outer edges. This is due to inadequate commixture of stuff and distribution cell suspension in the dishes. The per centum of cell coverage did correlate in some instances to the cell figure, but the BHK cells in media incorporating 2 % and 10 % FCS, they did non correlate as closely, particularly the BHK cells in 2 % FCS.

It must be noted that the duplicating times calculated are extremely inaccurate due to really little figure of informations points collected, particularly for HeLa and BHK 2 % FCS. This meant that the anomalous informations skewed the T1/2 measurings. In order to roll up more accurate informations, more samples would necessitate to be collected over the class of the experiment i.e. utilizing more clip points at smaller intervals e.g. every 12 hours alternatively of every 24 hours. However, this could merely be achieved by roll uping informations early in the forenoon and so in the eventide, which may be impossible due to clip constrains.

The BHK cells in GMEM/2 % FCS produced some unusual spectrophotometer reading, since the reading at 72 hours was around half the value at 48 hours and the value read at 96 hours was besides low. This affected the protein concentration in the civilization read from Figure 3 ( see appendix ) and therefore the deliberate values for the sum of protein released from each cell, entire cell Numberss and T1/2. The T1/2 was really high, at 205.7 hours compared to the remainder of the civilizations, doing it hard to compare this civilization against the other civilizations with any grade of truth. Reasons for the low cell figure calculated may include mistake in measuring of reagents used during readying of the civilization or during the harvest home of the civilization, ensuing in denaturation of protein and therefore bring forth a lower optical density. Other possible accounts are taint of one or more of the samples of this civilization or extended protein denaturation due to the stop deading procedure in the 72 hr infusion. The lone manner this could hold been rectified would hold been to reiterate the passing and incubation of this peculiar civilization but clip restraints and deficiency of stuffs did non let for this.

The cell Numberss of the remainder of the civilizations increased over the class of the experiment, as expected, and produced duplicating times that lay within the clip bounds of the experiential protocol.

HeLa cells in DMEM/2 % FCS: The concluding two information points, of the samples harvested at 72 and 96 hours correlated with the per centum coverage informations, though the point at 48 hours was much lower. This anomalous value is one of the lowest cell Numberss calculated, which indicates that there was a error made during readying of the civilization for incubation or harvest home. This has skewed the gradient, doing it steeper than it otherwise might hold been and resulted in the highest doubling clip.

HeLa cells in DMEM/10 % FCS correlated to the corresponding graph on Figure 1, although the gradient is steeper than that in Figure 1. The difference may be due to the civilization non being equally distributed and hence an inaccurate estimation of estimated per centum screen being recorded. As the cells were incubated over the class of the experiment, the cell Numberss increased.

BHK cells in GMEM/10 % FCS: to the corresponding graph on Figure 1, and has a similar gradient, although the value at 48 hours is somewhat higher than the tendency line. The first clip point is the lowest on figure 1, and the points at 72 and 96 hours are the highest. This civilization had the 2nd highest duplicating clip, merely somewhat lower than that of the HeLa cells in DMEM/2 % FCS. Due to the fact that the HeLa civilization had fewer clip points and an anomalous consequence that was more considerable that the anomalousness in the BHK civilization in 10 % FCS can be considered to hold the highest rate of growing due to a larger overall addition in cell figure.

From the cell figure of each civilization, it can be concluded that the cells of both cell lines grown in 10 % Foetal Calf Serum reached higher entire cell Numberss, but that the HeLa cell line in 10 % FCS grew with the fastest doubling clip. The BHK cells in 2 % FCS grew really rapidly during the first 48 hours and reached the greatest cell figure of all the civilizations at 48 hours. Taking into history the visual aspect of the informations on Figure 2 and the slow T1/2, every bit good as the fact that the cells grew at the fastest rate before information was taken, it is hard to make a decision about this information in relation to the other cell civilizations. . Had the value at 48 hours non been out of the blue high and a value collected at 24 hours, the T1/2 would really probably be much lower and closer to that of the HeLa civilization in 2 % FCS. However, it is clear that both cell lines incubated in 2 % FCS reaches lower entire cell Numberss than the civilizations of the same cell line in 10 % FCS. Therefore, it can be suggested that, since the cells grown in 2 % serum have a lower concentration of foods, and are non able to proliferate to bring forth cell Numberss every bit high as cells grown in 10 % serum. The BHK cells in 10 % serum have the fastest doubling clip.

Harmonizing to Figure 1, the Numberss of BHK cells incubated in both serum concentrations addition at a greater rate than the HeLa cells, ensuing in greater per centum coverage at the terminal of the experiment. Figure 2 reveals that the Numberss of BHK cells incubated in 10 % serum addition at a similar rate to that recorded on Figure 1. Taken together, this grounds indicates that the BHK cells are more fecund in cell civilization. Given the nature of the cell types, this would be expected. Baby Hamster Kidney Fibroblasts are fusiform cells that are responsible for synthesizing fibrillar extracellular matrix and collagen and therefore hold a comparatively high metabolic rate and proliferate quickly due to the demand for high turnover of ECM in the kidney3. HeLa cells, on the other manus, are transformed cervical carcinoma cells that proliferate quickly, and are a normally used cell line in biological research. However, even though they are carcinomas and therefore proliferate at a greater rate than many cell types, cervical cells do non proliferate every bit quickly as fibroblasts.

Harmonizing to the duplicating times collected, the optimum serum concentration for HeLa cells is 2 % and for BHK cells, 10 % since these consequence in the shortest duplicating times. It may be that HeLa cells do so proliferate at the optimal rate in 2 % serum since 10 % serum is excessively concentrated for this peculiar cell line. However, since the consequences are so blemished due to experimental mistake, it is hard to make a decision about the affect of serum concentration on the growing of cells in civilization.

The serum concentration greatly affected the entire cell figure over the class of the experiment, in that at greater serum concentration, the civilizations reached a greater entire cell figure. However, the civilizations incubated in lower concentrations of serum appeared to duplicate in figure more quickly, but non make cell Numberss every bit high as the civilizations grown in a higher concentration of serum.


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