The makers of Saved By The Bell have apologised to Selena Gomez for a joke made in a recent episode about her kidney transplant.
A spokesperson for NBC said it was "never our intention" to joke about her surgery.
The rebooted series features an episode where two characters argue over who donated a kidney to the singer in 2017.
NBC also said they had been in touch with Gomez about making a donation to her charity.
Selena, 28, received a kidney transplant three years ago after being diagnosed with the autoimmune disease Lupus.
The characters in Saved By The Bell speculated in a scene about who donated the kidney - with one claiming it was Demi Lovato and another saying it was Justin Bieber's mum.
Later in the episode, graffiti appears on the wall saying, "does Selena Gomez even have kidneys?"
She does, and one of them was donated by best friend Francia Raisa.
Francia has since tweeted about the episode, praising other donors for performing a "selfless act".
Fiona Loud is the head of policy at charity Kidney Care UK and has received a kidney herself.
She says donating a kidney is "one of the most selfless things a person can do" for a friend, family member or a stranger.
"This extraordinary generosity transforms lives and is something to be respected, rather than be made fun of.
"Every day in the UK around 20 people will develop kidney failure and sadly at least one person will die every day in need of a kidney transplant.
"We would like to give our utmost thanks and appreciation to amazing kidney donors like Francia Raisa."
According to the NHS, it's a long-term health condition that causes joint pain, skin rashes and tiredness.
It has no cure and can also cause headaches, mouth sores, a high temperature and hair loss.
It is not easy to diagnose because it has similar symptoms to other conditions but a blood test will usually reveal the condition if high levels of a type of antibody are found.