1namespace Crop.Retorna
2{
3    using System.Text.RegularExpressions;
4
5    public class cropRetorna
6    {
7        public string CropSentence(string textCrop, int num, string trail)
8        {
9            int iMax;
10            Regex rx = new Regex("<[^>]*>");
11                   
12            textCrop = rx.Replace(textCrop, "");
13
14            iMax = num - trail.Length;
15
16            if (iMax <= 0)
17            {
18                return "";
19            }
20            else if (textCrop.Length <= num)
21            {
22                return textCrop;
23            }
24            else
25            {
26                #region Crop   ...
27
28
29                string sOut;
30                sOut = textCrop.Substring(0, num);
31
32                int iPos;
33                iPos = sOut.LastIndexOf(" ");
34
35                return sOut.Substring(0, iPos) + trail;
36                #endregion
37            }
38        }
39    }
40}

no DataBound do controle

if (e.Row.RowType == DataControlRowType.DataRow)
        {
            cropRetorna CR = new cropRetorna();
            e.Row.Cells[0].Text =
                CR.CropSentence(DataBinder.Eval(e.Row.DataItem, "Campo").ToString(), 100, " ...").ToString();
        }