Why does my variable gets overwritten by the next characters in my for loop in BASH when I echo'ed?

Question

So this behavior is really weird. I have always accessed a file line by line, get that variable in $i and then grep this value from a file to output to a file, but now it looks that everything up to the variable is being overwritten with the characters after the variables. Look:

for i in $(cat tissues); do echo "grep -w $i";done
grep -w AdiposeTissue
grep -w AdrenalGland
grep -w Bladder

Then when I do (some examples) :

for i in $(cat tissues); do echo "grep -w $i AnyInterestingFile.txt";done
 AnyInterestingFile.txt
 AnyInterestingFile.txt
 AnyInterestingFile.txt

for i in $(cat tissues); do echo "grep -w $i AnyInterestingFile.txt param1 param2";done
 AnyInterestingFile.txt param1 param2
 AnyInterestingFile.txt param1 param2
 AnyInterestingFile.txt param1 param2

for i in $(cat tissues); do echo "grep -w $i Anyfile";done
 AnyfileAdiposeTissue
 AnyfileAdrenalGland
 AnyfileBladder