  The stability of hole bound states in the t-J model including short-range
Coulomb interactions is analyzed using computational techniques on ladders with
up to $2 \times 30$ sites. For a nearest-neighbors (NN) hole-hole repulsion,
the two-holes bound state is surprisingly robust and breaks only when the
repulsion is several times the exchange $J$. At $\sim 10%$ hole doping the
pairs break only for a NN-repulsion as large as $V \sim 4J$. Pair-pair
correlations remain robust in the regime of hole binding. The results support
electronic hole-pairing mechanisms on ladders based on holes moving in
spin-liquid backgrounds. Implications in two dimensions are also presented. The
need for better estimations of the range and strength of the Coulomb
interaction in copper-oxides is remarked.
