Apparatus, comprising: a sheath (22), advanceable through an endoscope (10), and having distal openings comprising a first opening (30a) and a plurality of second openings (30b) surrounding the first opening; a housing (24), coupled to a proximal portion of the sheath; a first needle (28a), extending through the housing and sheath toward the first opening; a plurality of second needles (28b), extending through the housing and sheath toward a respective second opening; a first handle (26a), slidably coupled to the housing along an axis such that the first needle slides through the sheath and a distal tip of the first needle moves with respect to the first opening; and a second handle (26b), slidably coupled to the housing along a different axis such that the second needles slide through the sheath and a distal tip of each second needle moves with respect to its respective second opening.