Property and equipment, net consisted of the following (in thousands):


	September 30, 2023			December 31, 2022
Laboratory equipment	$	513		$	679
Software and computer equipment		377			383
Machinery and equipment		440			450
Furniture and fixtures		48			83
Vehicles		302			306
Leasehold improvements		1,590			1,590
Property and equipment, gross		3,270			3,491
Less: accumulated depreciation and amortization		(2,802	)		(2,811	)
Property and equipment, net	$	468		$	680

Depreciation expense was $89,000 and $227,000 for the three and nine months ended September 30, 2023, respectively. Depreciation expense was $77,000 and $354,000 for the three and nine months ended September 30, 2022, respectively.

As of December 31, 2022, there was $10,000 of construction in progress included in property and equipment that had not been placed into service and was not subject to depreciation. As of September 30, 2023, there was no construction in progress included in property and equipment.

Property and equipment are considered assets held for sale when management approves and commits to a plan to dispose of a property or group of properties. The property and equipment held for sale prior to the sale date is separately presented, within current assets, on the condensed consolidated balance sheet as assets held for sale.

During the three and nine months ended September 30, 2023, management sold property and equipment and realized a gain on sale of $11,000 and $36,000, respectively, recorded on the condensed consolidated statements of operations and comprehensive loss, with proceeds of $5,000 and $42,000, respectively. During the three and nine months ended September 30, 2022, management initiated the sale of property and equipment related to the Davis laboratory and Archipelago, respectively. The Company completed the sale of a portion of such property and equipment with a gain on sale of property and equipment in the amount of $0 and $386,000 recorded on the condensed consolidated statements of operations and comprehensive loss during the three and nine months ended September 30, 2022, respectively. The proceeds related to the sale of property and equipment during the three and nine months ended September 30, 2022 were $5,000 and $897,000, respectively.

Property and equipment related to Archipelago, in the amount of $87,000, have been classified as assets held for sale, and are recorded at fair value as of September 30, 2023 and December 31, 2022. The fair value has been estimated using publicly available prices for some of the assets, and business partners' estimates for assets with prices not readily available, due to the relatively small size of the industry in which they can be used. In October 2023, the Company sold some of these assets for total proceeds of $65,000.