A.rows = [11,12,13,14,15]; % numeric vector
A.cols = {'A','B','C','D','E'}; % cell of strings
A.in = magic(5);  % numeric matrix
DS = mat2dataset(A.in,'VarNames',A.cols, 'ObsNames',cellstr(num2str(A.rows')));
export(DS,'file','A.txt') %

type A.txt

A <- read.table('A.txt',header = TRUE)

head(A)
#  Observations  A  B  C  D  E
# 1           11 17 24  1  8 15
# 2           12 23  5  7 14 16
# 3           13  4  6 13 20 22
# 4           14 10 12 19 21  3
# 5           15 11 18 25  2  9