Isla, seven, was diagnosed with the rare childhood cancer neuroblastoma at the age of two, underwent lifesaving surgery at London´s Great Ormond Street Hospital and has been receiving pioneering medical treatment in the Spanish city of Barcelona.
The brave young West Ham fan, from Hornchurch in Essex, suffered a relapse just before Christmas after returning to the UK and has now returned to Spain, where she is doing well.
Mr Sečka, who has become a big West Ham supporter following the arrivals of Tomáš Souček and Vladimír Coufal at London Stadium, was made aware of Isla´s fight and reached out to both players and the Club, as well as their former club Slavia Prague, to help.
The Ambassador has secured signed shirts from Souček and Coufal and - in cooperation with Slavia - also from the centre forward of the Red-whites Abdallah Sima, whose goals have helped the Czech side reach the UEFA Europa League round of 16, where they face Scottish club Rangers FC.
An auction to raise funds for Isla´s fight will launch at 9am on Thursday 11 March. To make a bid for one of the three signed shirts, click here.
Proceeds raised from the auction will be donated to the Isla´s fight fund.
Mr Sečka said: "Football is a game, but is also a powerfull tool in connecting people. And I am very happy that in the case of little Isla´s fight we can all unite. I am grateful to Slavia Praha, West Ham United, to their players and their fans that thanks to their enormous solidarity and compassion we can jointly develop a very useful thing. I very much hope that this will help to our little great Isla!"
"As West Ham players, we know about this brave little girl Isla and her fight and we wanted to do what we can to help raise funds for her treatment. We spoke with Mr Sečka, who has become a big fan of the Hammers, and we have donated signed shirts which we hope will raise lots of money," Souček and Coufal said.
To make a bid for one of the signed shirts, click here now.