TLR4 and brain infarction: The main findings were summarized as follows: (1) A single systemic administration of 10 μg cell‐free DPSC‐Exos could significantly attenuate the cerebral infarction, brain oedema and neurological impairment in I/R mice; (2) DPSC‐Exos could alleviate the neuroinflammation of ischaemic challenged brain and oxygen‐ and glucose‐deprived BV2 cells; (3) HMGB1/TLR4/MyD88/NF‐κB pathway was activated by cerebral I/R, and DPSC‐Exos inhibited the neuroinflammatory reaction via the HMGB1/TLR4/MyD88/NF‐κB pathway in cerebral I/R mice.