Is it permissible for a person suffering from a chronic illness, who is 56 years old and in debt, to secure the necessary funds for Hajj from relatives or friends or by selling some of his possessions?

The questioner did not understand the intent of his own question. If he means, "Should he take out a loan for Hajj?", then it is not advisable to borrow for that, as Hajj is only obligatory upon the one who is able. If he possesses more than his needs, he should sell it to pay off his debt. If what remains is sufficient for Hajj, then it becomes obligatory upon him. Otherwise, he should not take out a loan, for fear of dying and his debt remaining outstanding, due to the Prophet, peace and blessings be upon him, saying: "The soul of a believer remains suspended by his debt until it is paid off on his behalf."