PHP，PDO fetchAll如何反序列化特定的行

As title, i use php PDO connection how to unserialize row['node_relation'] row when i use fetchAll(PDO::FETCH_ASSOC)

Here's the data in DB:

arrow_sn | x1 | x2 | y1 | y2 | node_relation
830      | 365| 334| 545| 389| s:11:"1-A-1,2-A-2";

Here's the code:

$nodesData = $dbh->prepare("SELECT * FROM map_node");
    $nodesData->execute();
    $row = $nodesData -> fetchAll(PDO::FETCH_ASSOC);
    echo json_encode($row);